Peritoneal dialysis system including manifold assembly and peristaltic pump

ABSTRACT

A peritoneal dialysis (“RD”) system includes a cycler including an actuation surface having a peristaltic pump actuator; a manifold assembly including a rigid manifold having first and second chambers (110a, 110b), the rigid manifold configured and arranged to be abutted against the actuation surface for operation, a peristaltic pump tube (124gh) extending from the first chamber (110a) to the second chamber (110b) of the rigid manifold, a dialysis fluid container line (124b) extending from the first chamber (110a), and a branch line (124c) extending between the dialysis fluid container line (124b) and the second chamber (110b); and a control unit configured to cause the peristaltic pump actuator to actuate the peristaltic pump tube (124gh) to pump dialysis fluid from the branch line (124c) into the second chamber (100b) and from the second chamber (110b) into the first chamber (110a).

PRIORITY CLAIM

The present application claims priority to and the benefit of U.S.Provisional Application 63/123,796, filed Dec. 10, 2020, the entirety ofwhich is herein incorporated by reference.

BACKGROUND

The present disclosure relates generally to medical fluid treatments andin particular to dialysis fluid treatments.

Due to various causes, a person's renal system can fail. Renal failureproduces several physiological derangements. It is no longer possible tobalance water and minerals or to excrete daily metabolic load. Toxic endproducts of metabolism, such as, urea, creatinine, uric acid and others,may accumulate in a patient's blood and tissue.

Reduced kidney function and, above all, kidney failure is treated withdialysis. Dialysis removes waste, toxins and excess water from the bodythat normal functioning kidneys would otherwise remove. Dialysistreatment for replacement of kidney functions is critical to many peoplebecause the treatment is lifesaving.

One type of kidney failure therapy is Hemodialysis (“HD”), which ingeneral uses diffusion to remove waste products from a patient's blood.A diffusive gradient occurs across the semi-permeable dialyzer betweenthe blood and an electrolyte solution called dialysate or dialysis fluidto cause diffusion.

Hemofiltration (“HF”) is an alternative renal replacement therapy thatrelies on a convective transport of toxins from the patient's blood. HFis accomplished by adding substitution or replacement fluid to theextracorporeal circuit during treatment. The substitution fluid and thefluid accumulated by the patient in between treatments is ultrafilteredover the course of the HF treatment, providing a convective transportmechanism that is particularly beneficial in removing middle and largemolecules.

Hemodiafiltration (“HDF”) is a treatment modality that combinesconvective and diffusive clearances. HDF uses dialysis fluid flowingthrough a dialyzer, similar to standard hemodialysis, to providediffusive clearance. In addition, substitution solution is provideddirectly to the extracorporeal circuit, providing convective clearance.

Most HD, HF, and HDF treatments occur in centers. A trend towards homehemodialysis (“HHD”) exists today in part because HHD can be performeddaily, offering therapeutic benefits over in-center hemodialysistreatments, which occur typically bi- or tri-weekly. Studies have shownthat more frequent treatments remove more toxins and waste products andrender less interdialytic fluid overload than a patient receiving lessfrequent but perhaps longer treatments. A patient receiving morefrequent treatments does not experience as much of a down cycle (swingsin fluids and toxins) as does an in-center patient, who has built-up twoor three days' worth of toxins prior to a treatment. In certain areas,the closest dialysis center can be many miles from the patient's home,causing door-to-door treatment time to consume a large portion of theday. Treatments in centers close to the patient's home may also consumea large portion of the patient's day. HHD can take place overnight orduring the day while the patient relaxes, works or is otherwiseproductive.

Another type of kidney failure therapy is peritoneal dialysis (“PD”),which infuses a dialysis solution, also called dialysis fluid, into apatient's peritoneal chamber via a catheter. The dialysis fluid is incontact with the peritoneal membrane in the patient's peritonealchamber. Waste, toxins and excess water pass from the patient'sbloodstream, through the capillaries in the peritoneal membrane, andinto the dialysis fluid due to diffusion and osmosis, i.e., an osmoticgradient occurs across the membrane. An osmotic agent in the PD dialysisfluid provides the osmotic gradient. Used or spent dialysis fluid isdrained from the patient, removing waste, toxins and excess water fromthe patient. This cycle is repeated, e.g., multiple times.

There are various types of peritoneal dialysis therapies, includingcontinuous ambulatory peritoneal dialysis (“CAPD”), automated peritonealdialysis (“APD”), tidal flow dialysis and continuous flow peritonealdialysis (“CFPD”). CAPD is a manual dialysis treatment. Here, thepatient manually connects an implanted catheter to a drain to allow usedor spent dialysis fluid to drain from the peritoneal chamber. Thepatient then switches fluid communication so that the patient cathetercommunicates with a bag of fresh dialysis fluid to infuse the freshdialysis fluid through the catheter and into the patient. The patientdisconnects the catheter from the fresh dialysis fluid bag and allowsthe dialysis fluid to dwell within the peritoneal chamber, wherein thetransfer of waste, toxins and excess water takes place. After a dwellperiod, the patient repeats the manual dialysis procedure, for example,four times per day. Manual peritoneal dialysis requires a significantamount of time and effort from the patient, leaving ample room forimprovement.

Automated peritoneal dialysis (“APD”) is similar to CAPD in that thedialysis treatment includes drain, fill and dwell cycles. APD machines,however, perform the cycles automatically, typically while the patientsleeps. APD machines free patients from having to manually perform thetreatment cycles and from having to transport supplies during the day.APD machines connect fluidly to an implanted catheter, to a source orbag of fresh dialysis fluid and to a fluid drain. APD machines pumpfresh dialysis fluid from a dialysis fluid source, through the catheterand into the patient's peritoneal chamber. APD machines also allow forthe dialysis fluid to dwell within the chamber and for the transfer ofwaste, toxins and excess water to take place. The source may includemultiple liters of dialysis fluid including several solution bags.

APD machines pump used or spent dialysate from the patient's peritonealcavity, though the catheter, and to the drain. As with the manualprocess, several drain, fill and dwell cycles occur during dialysis. A“last fill” may occur at the end of the APD treatment. The last fillfluid may remain in the peritoneal chamber of the patient until thestart of the next treatment, or may be manually emptied at some pointduring the day.

Known APD systems include a machine or cycler that accepts and actuatesa pumping cassette having a hard part and a soft part that is deformablefor performing pumping and valving operations. Sealing the fluiddisposable cassette with a pneumatic path via a gasket to provideactuation has proven to be a potential field issue, which can delaytreatment start time and affect user experience. Pneumatic cassettesystems also produce acoustic noise, which may be a source of customerdissatisfaction.

For each of the above reasons, an improved APD machine is needed.

SUMMARY

The present disclosure sets forth a streamlined automated peritonealdialysis (“APD”) cycler and associated system providing a peristalticpump and a manifold assembly that organizes tubing and performs manyfunctions discussed below. The manifold assembly includes a rigidplastic manifold, which in an embodiment is covered on one side by aplastic sheet for its for ease and cost of manufacturing. In anotherembodiment, a rigid plastic lid is ultrasonically welded onto the restof the rigid plastic manifold. The lid may include a slight ridge aroundits perimeter to aid in the rigidity of the lid.

The rigid plastic manifold is inserted inside of an APD cycler, forexample, in between an actuation surface and a door of the APD cycler.The door for example hinges open along a bottom of the cycler housingadjacent to the actuation surface. In one implementation, the rigidplastic manifold of the manifold assembly is mounted so that the plasticsheet of the manifold is located on the surface facing the door and isconstrained by the door during operation. The APD cycler includes aperistaltic pump head, which is able to be actuated in two directions bya motor located within the housing of the APD cycler. Pinch valves areprovided along the actuation surface of the APD cycler to selectivelyocclude tubing that extends from the rigid plastic manifold. An airsensor may be located along the actuation surface, e.g., behind wherethe patient line of the manifold assembly is mounted for operation.

When the rigid plastic manifold is mounted to the actuation surface foroperation, ports for receiving tubes extend from both sides of themanifold, e.g., from the right and left sides of the manifold. Portsextending from one side of the manifold (e.g., right side viewing APDcycler from the front) connect sealingly to a peristaltic pumping tube,while the ports from the other side of the manifold (e.g., to the leftside viewing APD cycler from the front) are, for example, from top tobottom, a drain port, a first heater line/first dialysis fluidcontainer, a bypass or branch line port, a second dialysis fluidcontainer port, a third dialysis fluid container port and a patient lineport. The number of ports provided by each of an upper and a lowerchamber are not limited by the number shown and described hereinembodiment and may be more or less than shown and described.

The rigid plastic manifold includes a rigid plastic wall that opposesthe plastic sheet. The plastic wall abuts up against the actuationsurface for operation. One or more apertures, such as circular holes,are formed or provided in the rigid plastic wall. The circular holes arecovered with pressure sensing membranes. When the manifold is mounted tothe APD cycler for operation, the pressure sensing membranes abutagainst pressure transducers. The pressure sensors or transducers sensethe pressure of fresh and used dialysis fluid entering and leaving themanifold.

A pressure sensing hole and accompanying pressure sensing membrane isprovided in the rigid plastic wall of each of the upper and the lowerchamber of the rigid plastic manifold. The upper chamber is the primaryair collecting chamber, which communicates with the drain port forremoving air to drain. The lower chamber communicates fluidly with thelower-most patient line port, which is the most important location to befree of air, wherein air in the patient line naturally tends to buoyupwards away from the patient line and into the lower chamber. In analternative embodiment, the pressure sensing apertures and correspondingpressure sensing membranes in the rigid plastic wall are provided alongan air channel extending away from the upper and/or lower chamber of themanifold.

A drain line and first dialysis fluid container/heater line extend andconnect to their respective ports, which communicate fluidly with theupper chamber. A Y-connection or branch line, a second dialysis fluidcontainer line, a third dialysis fluid container line and a patient lineextend and connect to their respective ports, which communicate fluidlywith the lower chamber. A peristaltic pumping tube extends between andconnects to respective ports of the upper and lower chambers. In anembodiment, a peristaltic pump actuator located at the actuation surfaceof the APD cycler rotates in a first direction to pump fresh, heateddialysis fluid from the upper chamber, through the peristaltic pumpingtube, to the lower chamber, and to the patient. The peristaltic pumpactuator rotates in the opposite direction to pump used dialysis fluidfrom the lower chamber, through the peristaltic pumping tube, to theupper chamber, and to drain.

The peristaltic pump actuator also rotates in the opposite direction topump fresh dialysis fluid from either of the second or third dialysisfluid containers into the lower chamber, through the peristaltic pumpingtube, to the upper chamber, and to the previously emptied first dialysisfluid container, which is placed in operable communication with adialysis fluid heater. By allowing the fresh dialysis fluid from each ofthe dialysis fluid containers to be heated in the first dialysis fluidcontainer, the disposable dialysis fluid set only has to be loaded oncefor operation. Additionally, a separate dialysis fluid heating containeror bag is not needed.

The first dialysis fluid container is loaded onto dialysis fluid heaterfor treatment. After the first dialysis fluid container is emptied, theperistaltic pump actuator reverses and pulls fluid from the seconddialysis fluid container and pushes same into the first dialysis fluidcontainer for heating. The same procedure is performed for the thirddialysis fluid supply container when the second dialysis fluid supplycontainer is emptied. If the dialysis fluid from the second (or third)container is different than that of the first container, theY-connection or branch line is used to enable the remaining fluid fromthe first dialysis fluid supply container to be pulled by theperistaltic pump actuator into the lower chamber and then pushed intothe upper chamber and out to drain before the differently formulatedfluid of the second (or third) dialysis fluid container is delivered tothe first dialysis fluid container for heating.

In one embodiment, each of the upper and lower chambers of the manifoldis provided with a plurality of pegs extending inwardly from the rigidplastic wall, which prevent the flexible plastic sheet from collapsingunder negative pressure. If the flexible sheet is instead replaced witha rigid plastic lid then the pegs are not needed. A certain portion ofthe rigid plastic wall for each of the upper and lower chambers is notprovided with pegs and serves as a capacitive sensing area for therespective upper or lower chamber. Each of the capacitive sensing areasof the rigid plastic wall during operation presses up against acapacitive sensing plate or electrode located along the actuationsurface of the APD cycler. The door of the APD cycler is provided with amatching capacitive sensing plate or electrode for each chamber, whicheach directly oppose the capacitive sensing plates placed along theactuation surface. The matching upper and lower sets of capacitivesensing plates or electrodes form upper and lower capacitive sensors.The capacitive sensors, one for each chamber, detect an amount of air inthe respective chamber. If too much air accumulates, the APD cyclerstops its current routine and pushes the air to drain in a mannerdiscussed herein.

In addition to the detection of air, the APD system of the presentdisclosure uses capacitive level sensing to calibrate the peristalticpump actuator, which is performed in one embodiment when enough airbuilds in the upper chamber that an air purge to drain needs to beperformed. Here, prior to the purge, the peristaltic pump actuator isrotated in a direction to so as to pull fluid from the lower chamberinto the upper chamber of the rigid plastic manifold. The uppercapacitive sensor detects how much fluid accumulates in the upperchamber over a known amount of peristatic pump strokes or revolutions,so that the current volume/stroke of the peristaltic pump in the currentdirection may be calculated and used going forward when rotating theperistaltic pump actuator in that same direction, e.g., during patientdraining from the lower chamber to the upper chamber. The lowercapacitive sensor may be used additionally (for confirmation) oralternatively to detect how much fluid leaves the lower chamber over theknown amount of peristatic pump strokes or revolutions, for thecalculated volume/stroke of the peristaltic pump in the currentdirection.

Likewise, prior to the purge, the peristaltic pump actuator is rotatedin the opposite direction to push fluid from the upper chamber into thelower chamber of the rigid plastic manifold. The upper capacitive sensordetects how much fluid leaves the upper chamber over the known amount ofperistatic pump strokes or revolutions, so that the volume/stroke of theperistaltic pump in the opposite direction may be calculated and usedgoing forward when rotating the peristaltic pump actuator in that sameopposite direction, e.g., for patient filling. The lower capacitivesensor may be used in addition (for confirmation) or alternatively todetect how much fluid accumulates in the lower chamber over a knownamount of peristatic pump strokes or revolutions for the calculatedvolume/stroke of the peristaltic pump in the opposite direction.

In one embodiment, the upper capacitive sensor is used primarily forcalibrating the peristaltic pump stroke volume. The lower capacitivesensor is used mainly for air management, but may be used forconfirmation of the pump stroke volume calibration if needed. Thisconfiguration assumes however that air management is able to be handledin the lower chamber, which is likely in most instances. It should beappreciated however that if unwanted air from treatment does migrateinto the upper chamber, the upper capacitive sensor will detect such airand be used here for air management, e.g., output to a control unit totake corrective action.

In an alternative embodiment, the APD system of the present disclosureuses a three chamber rigid plastic manifold. The three chamber rigidplastic manifold may begin with the two chamber manifold just described,including all of its structure, functionality and alternatives.Additionally, a third chamber is located, e.g., molded, on top of theformer upper chamber, making it a middle chamber in the three chambermanifold. One or more aperture may be formed between the middle andupper chamber, however, it is contemplated that fluid does not flow fromthe middle chamber to the upper, third chamber. Instead, the upperchamber is provided to supply air to the middle chamber during acalibration sequence. It is contemplated to either move a pressuresensing hole and accompanying pressure sensing membrane from the upperchamber of the two chamber manifold to the upper chamber of the threechamber manifold or to add a pressure sensing hole and accompanyingpressure sensing membrane to the upper chamber of the three chambermanifold.

In an embodiment, at least one of the parallel plate capacitance sensorsare provided again for the three chamber manifold, here with the middlechamber and possibly the lower chamber. The added upper chamber is notintended to hold fluid and does not operate with capacitive sensingplates or electrodes accordingly in one embodiment.

The pumping operation of the alternative three chamber manifold is thesame in one embodiment as that for the two chamber manifold. The third,upper chamber is added to perform a calibration procedure for theperistaltic pump actuator. In a first step of the calibration procedure,fresh dialysis fluid is pulled from one of the dialysis fluid containersto prime the middle and lower chambers completely, as determined usingthe capacitance sensors, so that all air is pushed to drain. In a nextstep, the pinch valve for the branch line leading from the firstdialysis fluid container to the lower chamber is opened, and theperistaltic pump actuator is actuated at a known revolutions per minute(“rpm”) in a first direction so as to move dialysis fluid from themiddle chamber to the lower chamber until the middle chamber iscompletely empty as determined by the associated capacitance sensor,wherein fluid in the lower chamber migrates back through the open branchline into the first dialysis fluid container, air from the upper chamberis pulled into the middle chamber, and the flexible sheet covering thethird chamber bows inward into the upper chamber to compensate for theair that moves from the upper chamber to the middle chamber. The volumeof the middle chamber (V_(m)) is known and the time duration (Δt) neededto fully drain the middle chamber is measured. Knowing those twoparameters and the rpm of the pump actuator actuated in the drainingdirection allows the stroke volume per revolution in the chamberdraining direction to be calculated, namely, to be equal toV_(m)/Δt/rpm, e.g., in milliliters (“ml”)/rpm.

In a next step, wherein the pinch valve for the branch line leading fromthe first dialysis fluid container to the lower chamber remains open,and the peristaltic pump actuator is actuated at a known revolutions perminute (“rpm”) in a second direction so as to move dialysis fluid fromthe lower chamber to the middle chamber until the middle chamber iscompletely full as determined by the associated capacitance sensor,wherein fluid from the first dialysis fluid container flows through theopen branch line into the lower chamber and from the lower chamber tothe middle chamber, air is pushed from the middle chamber into the upperchamber, and the flexible sheet covering the upper chamber straightenswithin the upper chamber due to the air being pushed into the upperchamber by the dialysis fluid entering the middle chamber. The volume ofthe middle chamber (V_(m)) is known and the time duration (Δt) needed tofully fill the middle chamber is measured. Knowing those two parametersand the rpm of the pump actuator actuated in the chamber fillingdirection allows the stroke volume per revolution in the fillingdirection to be calculated, namely, to be equal to V_(m)/Δt/rpm, e.g.,in ml/rev.

Alternative rigid plastic manifolds are discussed herein for providingunlimited air into the corresponding manifold assemblies. A firstalternative manifold adds a dedicated air port to the top chamber.Connected to the port is a tube and connector containing a hydrophobicair filter. A pinch valve is added to the cycler for selectively openingand closing the air filter line, which is normally closed. The pinchvalve may be opened at any time air is needed for volumetriccalibration, wherein the peristaltic pump is used to draw in air into,e.g., the upper chamber of the first alternative unlimited airmanifolds.

A second alternative unlimited air manifold provides a dedicated airport on the back of the manifold. The air port is routed to the topchamber of the manifold via an air pathway. A hydrophobic air filter isattached to the air port. The cycler provides a seal, e.g., a springclosed and pneumatically opened seal, to normally seal the hydrophobicair filter closed. The cycler provides a pneumatic pump and possibly apneumatic supply tank to supply, e.g., negative pressure to overcome thespring force and open the seal to expose the hydrophobic filter. Thecycler accordingly includes at least one pneumatic valve to open andclose a pneumatic line leading to the seal. The pneumatic valve isnormally closed until air is needed in the manifold for a volumetriccalibration. The peristaltic pump is used again to draw in air into thetop chamber at any time and for any amount of air needed for thevolumetric calibration.

The APD cycler of the present disclosure includes a control unit havingone or more processor, one or more memory and a video controller thatcontrols a user interface, such as a touch screen user interface. Thecontrol unit receives signals from the capacitance sensors and isprogrammed to use the signals to look for air during treatment and torun any one or more of the calibration procedures discussed here. Thecontrol unit receives signals from other sensors, such as pressuresensors and temperature sensors, and is programmed for example to use(i) pressure sensor signals as feedback to control the motor for theperistaltic pump actuator to pump at or below safe positive and negativepatient pressure limits and (ii) temperature sensor signals to controlthe dialysis fluid heater to heat fresh dialysis fluid within the firstdialysis fluid container to body temperature, e.g., 37° C.

The control unit is configured to use the results of the peristalticpump calibration procedures discussed herein in determining how muchfresh PD fluid is delivered to the patient and how much used PD fluid isremoved from the patient. That is, knowing the latest volume perrevolution, the control unit counts the number of revolutions over apatient fill or patient drain (including partial revolutions) andmultiplies that number by the volume per revolution to determine thevolume of fluid filled or drained. It should be appreciated that thevolume per revolution could instead be weight per revolution (grams/rev)where the weight of fresh or used dialysis fluid within a particularchamber of the manifold is known.

It is contemplated to perform any of the calibration proceduresdiscussed herein prior to treatment to calibrate the peristaltic pump inboth counterclockwise and clockwise directions. The control unit maythen initially attempt to drain the patient. If no effluent is presentinitially, the control unit senses same and moves directly to a firstpatient fill. After the first fill and during a first patient dwell, andduring all subsequent patient dwells, the control unit repeats thecalibration procedure to recalibrate the peristaltic pump in bothcounterclockwise and clockwise directions. Patient fills and drains maybe performed using pressure and flow profiles, wherein lower pressuresand flowrates are used initially, followed by higher pressures andflowrates, e.g., for 80% to 90% of the patient fill or drain, andpossibly followed by a wind down period at the end of the patient fillor drain in which lower pressures and flowrates are used again.

The control unit also includes a transceiver and a wired or wirelessconnection to a network, e.g., the internet, for sending treatment datato and receiving prescription instructions from a doctor's orclinician's server interfacing with a doctor's or clinician's computer.In particular, the control unit may send data over the network regardingan analysis of the patient's effluent, wherein the data is used todetermine the effectiveness of the patient's APD treatment. The doctoror clinician may review the data to determine if the patient'sprescription should be modified, e.g., dwell times modified and/orchange in dialysis fluid formulation. The data sent from the APD cyclerto the network may be the same as, or akin to, data obtained from aperitoneal equilibration test (“PET”).

PETs determine the mass transport characteristics associated with thepatient's peritoneum. PETs help doctors and clinicians to decide whethera patient's PD treatment may be improved, e.g., using different dwelltimes and/or different PD fluid formulation. A full PET may take aroundfive hours to complete and may involve a CAPD exchange for example usinga 2.27% glucose solution. Samples of PD fluid and patient blood aretaken at set times. It is known that classical parameters of peritonealtransport such as glucose reabsorption and creatinine transport have adirect correlation with the ionic conductivity of patient effluent.Conductivity has also been used to distinguish patients with and withoutultrafiltration failure.

The capacitive sensing associated with the dual and three chamber rigidplastic manifolds of the present disclosure provides an opportunitydetermine the conductivity associated with both the fresh and useddialysis fluid and to use the measured and determined conductivities todevelop data and send the data via a network to locations that have theneed and ability to clinically analyze the data for the reasonsdiscussed above. In particular, the capacitance sensors of the presentmanifolds provide a measure of a liquid dielectric constant from which aconductivity value can be derived.

One possible test procedure is to fill both chambers of the manifoldwith fresh dialysis fluid and then measure the capacitance (f_(fresh)).That fluid is drained after which both chambers of the manifold arefilled with effluent and a second capacitance measurement is taken(f_(effluent)). The difference between the two readings(Δf=f_(fresh)−f_(effluent)) is determined, recorded in the memory of theAPD cycler and sent via the network to the doctor's or clinician'scomputer for clinical analysis.

The peritoneal effectiveness evaluation is advantageous for at leastthree reasons. First, the evaluation may be performed on a regularbasis, even per treatment or per patient drain if desired, withouthaving to make the patient travel to have a test performed. Second, thetest is easy to perform such that it does not unduly interrupttreatment. Third, the capacitance measurement is non-invasive, that is,it does not require a probe or electrode to contact the fluid beingsensed as is the case with typical conductivity sensors. Sterility andcost issues with such contact are thus avoided.

In light of the disclosure set forth herein, and without limiting thedisclosure in any way, in a first aspect, which may be combined with anyother aspect described herein, or portion thereof, a peritoneal dialysis(“PD”) system comprises a cycler including an actuation surface having aperistaltic pump actuator; a manifold assembly including a rigidmanifold having first and second chambers, the rigid manifold configuredand arranged to be abutted against the actuation surface for operation,a peristaltic pump tube extending from the first chamber to the secondchamber of the rigid manifold, a dialysis fluid container line extendingfrom the first chamber, and a branch line extending between the dialysisfluid container line and the second chamber; and a control unitconfigured to cause the peristaltic pump actuator to actuate theperistaltic pump tube to pump dialysis fluid from the branch line intothe second chamber and from the second chamber into the first chamber.

In a second aspect, which may be combined with any other aspectdescribed herein, or portion thereof, when the rigid manifold is abuttedagainst the actuation surface for operation, the first chamber is anupper chamber and the second chamber is a lower chamber.

In a third aspect, which may be combined with any other aspect describedherein, or portion thereof, the rigid manifold includes at least oneflexible sheet surface.

In a fourth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, at least one of the first andsecond chambers of the rigid manifold includes at least one pegextending inwardly to prevent the flexible sheet from collapsing undernegative pressure.

In a fifth aspect, which may be combined with any other aspect describedherein, or portion thereof, at least one of the first or second chambersof the rigid manifold includes a pressure sensing hole and a pressuresensing membrane covering the pressure sensing hole, the at least onepressure sensing membrane placed in registry with a corresponding atleast one pressure transducer when the rigid manifold is abutted againstthe actuation surface for operation.

In a sixth aspect, which may be combined with any other aspect describedherein, or portion thereof, the PD system includes an air channelextending from one of the first or second chambers to a pressure sensinghole and a hydrophobic filter covering the pressure sensing hole, thehydrophobic filter placed in registry with a corresponding pressuretransducer when the rigid manifold is abutted against the actuationsurface for operation, and wherein the hydrophobic filter allows fordirect pressure communication between the air channel and the pressuretransducer.

In a seventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes a drainline extending from the first chamber of the rigid manifold, and whereinthe control unit is configured to cause the peristaltic pump actuator toactuate the peristaltic pump tube to pump dialysis fluid from the branchline into the second chamber, from the second chamber into the firstchamber, and from the first chamber into the drain line.

In an eighth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the dialysis fluid container lineis a first dialysis fluid container line, and which includes a seconddialysis fluid container line extending from the second chamber, andwherein the control unit is configured to cause the peristaltic pumpactuator to actuate the peristaltic pump tube to pump dialysis fluidfrom the branch line into the second chamber and from the second chamberinto the first chamber when (i) first dialysis fluid remains in a firstdialysis fluid container in fluid communication with the first dialysisfluid container line after a patient fill and (ii) second dialysis fluidprovided in a second dialysis fluid container in fluid communicationwith the second dialysis fluid container line for a next patient fill isdifferent than the first dialysis fluid.

In a ninth aspect, which may be combined with any other aspect describedherein, or portion thereof, the dialysis fluid container line is a firstdialysis fluid container line, and which includes a second dialysisfluid container line extending from the second chamber, and wherein thecontrol unit is further configured to cause the peristaltic pumpactuator to actuate the peristaltic pump tube to pump dialysis fluidfrom a second dialysis fluid container in fluid communication with thesecond dialysis fluid container line into a first dialysis fluidcontainer in fluid communication with the first dialysis fluid containerline for heating the second dialysis fluid.

In a tenth aspect, which may be combined with any other aspect describedherein, or portion thereof, the cycler further includes a dialysis fluidheater, the manifold assembly configured such that a dialysis fluidcontainer in fluid communication with the dialysis fluid container lineis placed on the dialysis fluid heater for treatment.

In an eleventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes a patientline extending from the second chamber of the rigid manifold, andwherein the cycler includes an air sensor positioned and arranged at theactuation surface to operate with the patient line when the rigidmanifold is abutted against the actuation surface for operation.

In a twelfth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes a dialysisfluid container line valve and a branch line valve positioned andarranged at the actuation surface to operate with the dialysis fluidcontainer line and the branch line, respectively, when the rigidmanifold is abutted against the actuation surface for operation.

In a thirteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes at leastone pair of capacitive sensing plates operable with at least one of thefirst chamber or the second chamber of the rigid manifold when abuttedagainst the actuation surface for operation, and wherein the controlunit is configured to receive a signal from each of the at least onepair of capacitive sensing plates, the at least one signal indicative ofan amount of air in at least one of the first or second chambers.

In a fourteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes a door thatencloses the rigid manifold after the rigid manifold is abutted againstthe actuation surface for operation, the actuation surface containingone of the plates of the at least one pair of capacitive sensing plates,and the door containing the other plate of the at least one pair ofcapacitive sensing plates.

In a fifteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the at least one capacitivesensing plate contained by the actuation surface is parallel to anddirectly opposes the at least one capacitive sensing plate contained bythe door.

In a sixteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the rigid manifold includes athird chamber, the third chamber configured to at least one of (i)provide air for backfilling the first chamber when fluid is pumped fromthe first chamber to the second chamber during a calibration procedurefor the peristaltic pump actuator or (ii) accept air from the firstchamber when fluid is pumped from the second chamber to the firstchamber during the calibration procedure for the peristaltic pumpactuator.

In a seventeenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a peritoneal dialysis (“PD”)system comprises a cycler including an actuation surface having aperistaltic pump actuator, and at least one pair of capacitive sensingplates; a manifold assembly including a rigid manifold having first andsecond chambers, the rigid manifold configured and arranged to beabutted against the actuation surface for operation, wherein the atleast one pair of capacitive sensing plates is positioned to be operablewith at least one of the first chamber or the second chamber, and aperistaltic pump tube extending from the first chamber to the secondchamber of the rigid manifold; and a control unit configured to (i)cause the peristaltic pump actuator to actuate the peristaltic pump tubeto pump an amount of dialysis fluid from the second chamber to the firstchamber, (ii) receive a signal from each of the at least one pair ofcapacitive sensing plates, the at least one signal indicative of theamount of dialysis fluid pumped, (iii) count a number of revolutions ofthe peristaltic pump actuator needed to pump the amount of dialysisfluid from the second chamber to the first chamber, (iv) determine acurrent volume per revolution for the peristaltic pump actuator, and (v)use the current volume per revolution for at least one subsequentoperation of the peristaltic pump actuator.

In an eighteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the current volume per revolutionis for a first direction of the peristaltic pump actuator, and whereinthe control unit is further configured to (vi) cause the peristalticpump actuator to actuate the peristaltic pump tube in a second directionto pump another amount of dialysis fluid from the first chamber to thesecond chamber, (vii) receive a signal from each of the at least onepair of capacitive sensing plates, the at least one signal indicative ofthe other amount of dialysis fluid pumped, (viii) count a number ofrevolutions of the peristaltic pump actuator needed to pump the otheramount of dialysis fluid from the first chamber to the second chamber,(ix) determine a current volume per revolution for a second direction ofthe peristaltic pump actuator, and (x) use the current volume perrevolution for at least one subsequent operation of the peristaltic pumpactuator in the second direction.

In a nineteenth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the first direction is a patientdrain direction and the second direction is a patient fill direction.

In a twentieth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the first direction is also ato-dialysis fluid heater direction.

In a twenty-first aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the rigid manifold includes athird chamber, the third chamber configured to provide air forbackfilling the first chamber when the other amount of dialysis fluid ispumped from the first chamber to the second chamber.

In a twenty-second aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the rigid manifold includes athird chamber, the third chamber configured to accept air from the firstchamber when the amount of dialysis fluid is pumped from the secondchamber to the first chamber.

In a twenty-third aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured torepeat (i) to (v) of the seventeenth aspect in each of a plurality ofcycles of a PD treatment.

In a twenty-fourth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the number of revolutions takesinto account a fraction of a revolution.

In a twenty-fifth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured toperform (i) to (v) of the seventeenth aspect when a threshold amount ofair is sensed in one of the first or second chambers of the rigidmanifold.

In a twenty-sixth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes a firstpair of capacitive sensing plates operable with the first chamber and asecond pair of sensing plates operable with the second chamber, andwherein the control unit is configured in (ii) of the seventeenth aspectto receive a first signal from the first pair of capacitive sensingplates, the first signal indicative of the amount of dialysis fluidpumped to the first chamber, and to receive a second signal from thesecond pair of capacitive sensing plates, the second signal indicativeof the amount of dialysis fluid pumped from the second chamber.

In a twenty-seventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured toat least one of (i) determine a degree to which the first and secondsignals match, or (ii) average the first and second signals.

In a twenty-eighth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes a door thatencloses the rigid manifold after the rigid manifold is abutted againstthe actuation surface for operation, the actuation surface containingone of the plates of the at least one pair of capacitive sensing plates,and the door containing the other plate of the at least one pair ofcapacitive sensing plates.

In a twenty-ninth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the at least one capacitivesensing plate contained by the actuation surface is parallel to anddirectly opposes the at least one capacitive sensing plate contained bythe door.

In a thirtieth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, using the current volume perrevolution for at least one subsequent operation of the peristaltic pumpactuator includes multiplying the volume per revolution by a number ofrevolutions recorded by the control unit during each of the at least onesubsequent operation.

In a thirty-first aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit includes at leastone processor, at least one memory and may include at least one videocontroller.

In a thirty-second aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a peritoneal dialysis (“PD”)system comprises a cycler including an actuation surface having aperistaltic pump actuator, and at least one pair of capacitive sensingplates; a manifold assembly including a rigid manifold having at leastone chamber, the rigid manifold configured and arranged to be abuttedagainst the actuation surface for operation, wherein the at least onepair of capacitive sensing plates is positioned to be operable with theat least one chamber of the rigid manifold, and a peristaltic pump tubeincluding first and second ends in fluid communication with the rigidmanifold; and a control unit configured to (i) cause the peristalticpump actuator to actuate the peristaltic pump tube to pump an amount ofdialysis fluid to one of the at least one chamber, (ii) receive a signalfrom the pair of capacitive sensing plates associated with the chamber,the signal indicative of the amount of dialysis fluid pumped, (iii)count a number of revolutions of the peristaltic pump actuator needed topump the amount of dialysis fluid to the chamber, (iv) determine acurrent volume per revolution for the peristaltic pump actuator, and (v)use the current volume per revolution for at least one subsequentoperation of the peristaltic pump actuator.

In a thirty-third aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the current volume per revolutionis for a first direction of the peristaltic pump actuator, and whereinthe control unit is further configured to (vi) cause the peristalticpump actuator to actuate the peristaltic pump tube in a second directionto pump another amount of dialysis fluid from the chamber, (vii) receivea signal from the pair of capacitive sensing plates associated with thechamber, the signal indicative of the other amount of dialysis fluidpumped, (viii) count a number of revolutions of the peristaltic pumpactuator needed to pump the other amount of dialysis fluid from thechamber, (ix) determine a current volume per revolution for a seconddirection of the peristaltic pump actuator, and (x) use the currentvolume per revolution for at least one subsequent operation of theperistaltic pump actuator in the second direction.

In a thirty-fourth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured torepeat (i) to (v) of the thirty-second aspect in each of a plurality ofcycles of a PD treatment.

In a thirty-fifth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system is configured toexchange at least one of treatment or patient data over a network.

In a thirty-sixth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured toperform (i) to (v) of the thirty-second aspect when a threshold amountof air is sensed in the chamber of the rigid manifold.

In a thirty-seventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes a door thathinges closed against the rigid manifold after the rigid manifold isabutted against the actuation surface for operation, the actuationsurface containing one of the plates of the at least one pair ofcapacitive sensing plates, and the door containing the other plate ofthe at least one pair of capacitive sensing plates.

In a thirty-eighth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the at least one capacitivesensing plate contained by the actuation surface is at least one ofparallel to and directly opposing the at least one capacitive sensingplate contained by the door.

In a thirty-ninth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, using the current volume perrevolution for at least one subsequent operation of the peristaltic pumpactuator includes mathematically combining the volume per revolution bya number of revolutions recorded by the control unit during each of theat least one subsequent operation.

In a fortieth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes a dialysisfluid heater.

In a forty-first aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a peritoneal dialysis (“PD”)system comprises a cycler including an actuation surface having aperistaltic pump actuator, and a pair of capacitive sensing plates; amanifold assembly including a rigid manifold having first, second andthird chambers, the rigid manifold configured and arranged to be abuttedagainst the actuation surface for operation, wherein the pair ofcapacitive sensing plates is positioned to be operable with the firstchamber, and a peristaltic pump tube extending from the first chamber tothe second chamber of the rigid manifold; and a control unit configuredto (i) cause the peristaltic pump actuator to actuate the peristalticpump tube at a known revolutions per minute (“rpm”) to empty dialysisfluid from a full first chamber to the second chamber, wherein airbackfills the first chamber from the third chamber, (ii) receive asignal from the pair of capacitive sensing plates indicating that thefirst chamber is empty, (iii) record a time duration Δt needed to emptydialysis fluid from the full first chamber to the second chamber, (iv)determine a current volume per revolution for the peristaltic pumpactuator by performing a first division of a known volume of the firstchamber by the time duration Δt and a second division of a result of thefirst division by the known rpm, and (v) use the current volume perrevolution for at least one subsequent operation of the peristaltic pumpactuator.

In a forty-second aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured usethe signal from the pair of capacitive sensing plates to confirm thatthe first chamber is full of dialysis fluid prior to (i) of theforty-first aspect.

In a forty-third aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the current volume per revolutionis for a first direction of the peristaltic pump actuator, and whereinthe control unit is further configured to (vi) cause the peristalticpump actuator to actuate the peristaltic pump tube at a knownrevolutions per minute (“rpm”) in a second direction to fill firstchamber with dialysis fluid from the second chamber, wherein the thirdchamber accepts air displaced from the first chamber, (ii) receive asignal from the pair of capacitive sensing plates indicating that thefirst chamber is full, (iii) record a time duration Δt needed to filldialysis fluid from the second chamber to the first chamber, (iv)determine a current volume per revolution for the peristaltic pumpactuator in the second direction by performing a first division of aknown volume of the first chamber by the time duration Δt and a seconddivision of a result of the first division by the known rpm, and (v) usethe current volume per revolution in the second direction for at leastone subsequent operation of the peristaltic pump actuator.

In a forty-fourth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the first direction is a patientfill direction and the second direction is a patient drain direction.

In a forty-fifth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured torepeat (i) to (v) of the forty-first aspect in each of a plurality ofcycles of a PD treatment.

In a forty-sixth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes at least onevalve opening or closing at least one tube or line extending from therigid manifold.

In a forty-seventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the at least one valve is a pinchvalve.

In a forty-eighth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a dialysis fluid container influid communication with the rigid manifold operates as a dialysis fluidheating container.

In a forty-ninth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, an encoder is provided for usewith the peristaltic pump actuator, wherein the encoder allows a fullrevolution of 360° of the actuator to be divided into many fractions ofa rotation, e.g., into 5919 fractions.

In a fiftieth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a peritoneal dialysis (“PD”)system comprises a cycler including an actuation surface having aperistaltic pump actuator, and at least one pair of capacitive sensingplates; a manifold assembly including a rigid manifold having at leastone chamber, the rigid manifold configured and arranged to be abuttedagainst the actuation surface for operation, wherein the at least onepair of capacitive sensing plates is positioned to be operable with theat least one chamber of the rigid manifold, and a peristaltic pump tubeincluding first and second ends in fluid communication with the rigidmanifold; and a control unit configured to (i) cause the peristalticpump actuator to actuate the peristaltic pump tube to fill one of the atleast one chamber with fresh dialysis fluid, (ii) take a first readingfrom the pair of capacitive sensing plates associated with the chamber,the first reading indicative of a capacitance (f_(fresh)) associatedwith the chamber filled with fresh dialysis fluid, (iii) cause theperistaltic pump actuator to actuate the peristaltic pump tube to fillthe chamber with effluent, (iv) take a second reading from the pair ofcapacitive sensing plates associated with the chamber, the secondreading indicative of a capacitance (f_(effluent)) associated with thechamber filled with effluent, and (v) determine a difference (Δf)between the first and second readings.

In a fifty-first aspect, which may be combined with any other aspectdescribed herein, or portion thereof, (iii) and (iv) occur before (i)and (ii) of the fiftieth aspect.

In a fifty-second aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is furtherconfigured to convert the difference between the first and secondreadings (Δf) into peritoneal dialysis effectiveness data or send thedifference between the first and second readings (Δf) to a remotelocation for conversion into dialysis effectiveness data.

In a fifty-third aspect, which may be combined with any other aspectdescribed herein, or portion thereof, a peritoneal dialysis (“PD”)system comprises a cycler including an actuation surface having aperistaltic pump actuator, and at least one pair of capacitive sensingplates; a manifold assembly including a rigid manifold including achamber, the rigid manifold configured and arranged to be abuttedagainst the actuation surface for operation, wherein the at least onepair of capacitive sensing plates is positioned to be operable with thechamber of the rigid manifold, and an air port for allowing air into thechamber, and a peristaltic pump tube including first and second ends influid communication with the rigid manifold; and a control unitconfigured to (i) cause the peristaltic pump actuator to pull air intothe chamber via the air port, (ii) cause the peristaltic pump actuatorto actuate the peristaltic pump tube to pump an amount of dialysis fluidto the chamber to displace the air, (ii) receive a signal from the pairof capacitive sensing plates associated with the chamber, the signalindicative of the amount of dialysis fluid pumped, (iii) count a numberof revolutions of the peristaltic pump actuator needed to pump theamount of dialysis fluid to the chamber, (iv) determine a current volumeper revolution for the peristaltic pump actuator based on the countednumber of revolutions, and (v) use the current volume per revolution forat least one subsequent operation of the peristaltic pump actuator.

In a fifty-fourth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the manifold assembly includes anair port line in fluid communication with the air port, and whichincludes a hydrophobic filter located at a distal end of the air portline.

In a fifty-fifth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the cycler includes an air portvalve operating with the air port line, and wherein the control unit isconfigured to open the air port valve during (i) of the fifty-thirdaspect.

In a fifty-sixth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes ahydrophobic filter attached to the air port, wherein the cycler includesa seal operating with the hydrophobic filter, and wherein the controlunit is configured to remove the seal from the hydrophobic filter during(i) of the fifty-third aspect.

In a fifty-seventh aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the control unit is configured toopen a pneumatic valve to allow negative pressure to remove the sealfrom the hydrophobic filter.

In a fifty-eighth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, the PD system includes an air lineextending from the chamber to a hydrophobic filter allowing directpressure communication between fresh or used dialysis fluid in thechamber and a pressure transducer provided by the cycler.

In a fifty-ninth aspect, which may be combined with any other aspectdescribed herein, or portion thereof, any of the features, functionalityand alternatives described in connection with any one or more of FIGS. 1to 19 may be combined with any of the features, functionality andalternatives described in connection with any other of FIGS. 1 to 19 .

It is accordingly an advantage of the present disclosure to provide anAPD system having a manifold assembly and peristaltic pump.

It is another advantage of the present disclosure to provide an APDsystem that is portable to ultra-portable.

It is a further advantage of the present disclosure to provide an APDsystem that eliminates certain sealing issues present in known APDsystems.

It is yet a further advantage of the present disclosure to provide anAPD pump driven system that eliminates bulky pneumatic equipmentassociated with certain APD systems.

It is yet another advantage of the present disclosure to provide an APDsystem that manages peritoneal dialysis fluid flow so as to be withinsafe and comfortable patient pressure limits.

It is still a further advantage of the present disclosure to provide anAPD system that provides non-invasive peristaltic pump actuatorcalibration.

It is still another advantage of the present disclosure to provide anAPD system that provides an improved way of obtaining peritonealeffectiveness data.

Additional features and advantages are described in, and will beapparent from, the following Detailed Description and the Figures. Thefeatures and advantages described herein are not all-inclusive and, inparticular, many additional features and advantages will be apparent toone of ordinary skill in the art in view of the figures and description.Also, any particular embodiment does not have to have all of theadvantages listed herein and it is expressly contemplated to claimindividual advantageous embodiments separately. Moreover, it should benoted that the language used in the specification has been selectedprincipally for readability and instructional purposes, and not to limitthe scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of one embodiment for an actuation surfaceand rotatable door of an automated peritoneal dialysis (“APD”) cycleroperating with a disposable rigid plastic manifold of the APD system ofthe present disclosure.

FIGS. 2A to 2C are front, back and perspective views of one embodimentfor a disposable rigid plastic manifold of the APD system of the presentdisclosure.

FIG. 3 is a front view illustrating one embodiment of a flow regime forthe APD system of the plan view.

FIG. 4 is a side view of the disposable rigid plastic manifoldillustrating schematically one embodiment for the capacitive sensingplates or electrodes of the present disclosure.

FIG. 5 is a schematic diagram illustrating one embodiment of acapacitance sensor circuit of the present disclosure.

FIG. 6 is process flow diagram illustrating one embodiment of aperistaltic pump calibration procedure of the present disclosure.

FIG. 7 is a plot illustrating capacitance sensor output over time,wherein the illustrated duration of time Δt is used in the calibrationprocedure of FIG. 6 .

FIG. 8 is a plot comparing an output of a capacitance sensor of thepresent disclosure against a weight scale output for the same fluidfill.

FIG. 9 is a plot showing an equation stored in software for convertingan output of a capacitance sensor of the present disclosure to adialysis fluid weight.

FIG. 10 is a front view illustrating one alternative disposable rigidplastic manifold of the APD system of the present disclosure.

FIG. 11 is a front view illustrating one embodiment of a flow regime forthe alternative manifold of FIG. 10 .

FIGS. 12A to 12C are side views taken along line 12A-12C of thealternative disposable rigid plastic manifold of FIG. 11 illustratingone possible peristaltic pump calibration procedure using the manifold.

FIGS. 13A to 13C illustrate one embodiment for providing an unlimitedsource of air to the disposable rigid plastic manifold of the presentdisclosure.

FIGS. 14A and 14B illustrate a second embodiment for providing anunlimited source of air to the disposable rigid plastic manifold of thepresent disclosure.

FIG. 15 illustrates a further alternative disposable rigid plasticmanifold of the present disclosure having an air passage for pressuresensing.

FIGS. 16 and 17 are schematic views helping to illustrate therelationship between capacitance and conductivity for a peritonealeffectiveness evaluation of the present disclosure.

FIG. 18 is a plot illustrating outputs of a capacitance sensor of thepresent disclosure for water at different sodium (conductivity) levels.

FIG. 19 is a plot illustrating outputs of a capacitance sensor of thepresent disclosure for dialysis fluid at different sodium (conductivity)levels.

DETAILED DESCRIPTION

Referring now to the drawings and in particular to FIGS. 1 and 2A to 2C,an embodiment of system 10 includes an automated peritoneal dialysis(“APD”) cycler 20 having a housing 22, which uses peristaltic pumping inthe illustrated embodiment and operates with a manifold assembly 100(FIG. 3 ) that organizes tubing and performs many functions discussedherein. Manifold assembly 100 includes a rigid plastic manifold 110,which in an embodiment is covered on one side by a flexible plasticsheet 112 for its for ease and cost of manufacturing. In an alternativeembodiment, plastic sheet 112 is instead a rigid lid, which is, forexample, ultrasonically welded to the rest of rigid manifold 110. Here,rigid lid 112 may include a slight ridge around its perimeter, whichaids in the rigidity of the lid. Rigid plastic manifold 110, plasticsheet 112 (flexible or rigid), the fluid lines and fluid containers(discussed below) of manifold assembly 100 may be made of one or moreplastic, e.g., polyvinylchloride (“PVC”) or a non-PVC material, such aspolyethylene (“PE”), polyurethane (“PU”) or polycarbonate (“PC”).Housing 22 of cycler 20 may be made of any of the above plastics, and/orof metal, e.g., stainless steel, steel and/or aluminum.

As illustrated in FIG. 1 , rigid plastic manifold 110 is mounted insideof APD cycler 20, for example, in between an actuation surface 24 and adoor 26 of the APD cycler. Door, for example, hinges open via one ormore hinge 28 located along a bottom of cycler housing 22, adjacent toactuation surface 24. In the illustrated implementation, rigid plasticmanifold 110 of manifold assembly 100 is mounted so that plastic sheet112 of manifold 110 is located on the surface facing door 26 (whenclosed), and so that manifold 110 is constrained by the door duringoperation.

APD cycler 20 includes a peristaltic pump head or actuator 30, which isable to be actuated in two directions by a motor 32, e.g., a stepper orbrushed or brushless DC motor, located within housing of the APD cycler.In an embodiment, electrical current supplied to motor 32 may be variedfor pressure control. For example, the current may be limited so thatpumping pressure to the patient for a patient fill is at or below apositive pressure threshold, e.g., 3 to 5 psig. The current may belimited so that pumping pressure from the patient for a patient drain isat or below a negative pressure threshold, e.g., −1.5 to −3 psig. Thecurrent may be higher for other pumping operations, e.g., positivepressure to drain and positive pressure to a dialysis fluid heatingcontainer, e.g., 7 psig.

Pinch valves 34 a to 34 f are provided along the actuation surface ofAPD cycler 20 to selectively occlude tubing that extends from the rigidplastic manifold. Tubing is discussed in detail below, but generally,pinch valve 34 a is a drain line pinch valve. Pinch valve 34 b is afirst dialysis fluid container/heating container valve. Pinch valve 34 cis a Y-connection or branch line valve. Pinch valve 34 d is a seconddialysis fluid container valve. Pinch valve 34 e is a third dialysisfluid container valve. Pinch valve 34 f is a patient line valve. Pinchvalves 34 a to 34 f are in one fail safe embodiment energized open andde-energized closed, electrically actuated pinch valves. In oneembodiment, the inner surface of door 26 provides the surface againstwhich pinch valves 34 a to 34 f occlude their respective tubing.

In the illustrated embodiment, actuation surface 24 defines grooves 24 ato 24 f for fitting and organizing the tubes of manifold assembly 100.Pinch valves 34 a to 34 f are located along grooves 24 a to 24 f,respectively. Groove 24 f of actuation surface 24 is also illustratedoperating with an optional air sensor 36, behind where the patient lineis mounted for operation. As discussed in detail below, air is detectedwithin rigid plastic manifold 110 and thus air sensor 36 is not beneeded. Air sensor 36 may however be provided in addition to thecapacitance air sensing discussed herein, e.g., as a last check beforefresh, heated dialysis fluid is delivered to the patient. Air sensor 36may also be provided if the capacitance air sensing discussed herein isnot employed.

When rigid plastic manifold 110 is mounted to actuation surface 24 foroperation, ports for receiving tubes extend from both sides of themanifold, e.g., from the right and left sides of the manifold. Portsfrom one side of manifold 110 (e.g., the left side viewing APD cyclerfrom the front in FIG. 1 ) are, for example, from top to bottom, a drainport 114 a, a first heater line/first dialysis fluid container port 114b, a bypass or branch line port 114 c, a second dialysis fluid containerport 114 d, a third dialysis fluid container port 114 e and a patientline port 114 f. Ports 114 g and 114 h extending from the other side ofmanifold 110 (e.g., right side viewing APD cycler from the front in FIG.1 ) connect sealingly to a peristaltic pumping tube 124 gh (see FIG. 3), which is actuated by peristaltic pump actuator 30.

Rigid plastic manifold 110 includes a rigid plastic wall 116 thatopposes plastic sheet 112. Rigid plastic wall 116 abuts up againstactuation surface 24 for operation. One or more apertures 118 a and 118b, such as circular holes, are formed or provided in rigid plastic wall116. Circular holes 118 a and 118 b are covered with pressure sensingmembranes. When manifold 110 is mounted to APD cycler 20 for operation,the pressure sensing membranes covering holes 118 a and 118 b abutagainst pressure transducers (not illustrated) provided by the cycler atactuation surface 24. The pressure sensors or transducers sense thepressure of fresh and used dialysis fluid entering and leaving themanifold, which is used as feedback for the electrical current controlof motor 32 to regulate fluid pumping pressures as discussed above.

A pressure sensing hole and accompanying pressure sensing membrane 118 aand 118 b is provided respectively in each of an upper chamber 110 a anda lower chamber 110 b of rigid plastic manifold 110. First or upperchamber 110 a is the primary air collecting chamber, which communicateswith drain port 114 a for removing air to drain (e.g., house drain ordrain container). Lower chamber 110 b communicates fluidly withlower-most patient line port 114 f, which is the most important locationto be free of air, wherein air in the lower chamber 10 b naturally tendsto buoy upwards away from patient line port 114 f. The number of ports114 a to 114 f provided by each of upper and lower chambers 110 a and 10b are not limited by the number shown and described herein embodimentand may be more or less than shown and described for either or bothchambers.

First or upper chamber 110 a includes a wall or walls 120 a that is/arecurved to help aid dialysis fluid flow from drain or dialysisfluid/heater ports 114 a and 114 b to peristaltic pump port 114 g orfrom peristaltic pump port 114 g to dialysis fluid/heater ports 114 aand 114 b. Second or lower chamber 110 b includes a wall 120 b thatextends up towards a top of lower chamber 110 b, leaving a small gap Gto allow dialysis fluid flow from branch line port 114 c, dialysis fluidports 114 d or 114 e or patient line port 114 f to peristaltic pump port114 h, or from peristaltic pump port 114 h to branch line port 114 c,dialysis fluid ports 114 d or 114 e or patient line port 114 f. Wall 120b forces the dialysis fluid to travel a longer, more tortuous path,allowing air more time and opportunity to migrate towards the top ofsecond or lower chamber 110 b. When a threshold amount of air is sensedin lower chamber 110 b, peristaltic pump actuator 30 is caused to rotatecounterclockwise in FIG. 1 to pump dialysis fluid to in turn push airfrom first or lower chamber 110 b into second or upper chamber 110 a,where it is removed to drain via drain port 114 a and associated drainline.

Rigid plastic manifold 110 is molded, e.g., injection or blow molded toform first and second chambers 110 a and 110 b, apertures 118 a and 118b, internal walls 120 a and 120 b, and pegs 122. In the illustratedembodiment, each of upper chamber 110 a and lower chamber 110 b ofmanifold 110 is provided with a plurality of pegs 122 extending inwardlyfrom the rigid plastic wall 116, which prevent flexible plastic sheet112 from collapsing under negative pressure. In the instance in whichplastic sheet 112 is instead a rigid plastic lid, pegs 122 are notneeded or provided.

Referring additionally to FIG. 3 , manifold assembly 100 is illustratedin more detail. A drain line 124 a and first dialysis fluidcontainer/heater line 124 b extend and connect to their respective ports114 a and 114 b, which communicate fluidly with upper chamber 110 a.Drain line 124 a and first dialysis fluid container/heater line 124 bare routed respectively in grooves 24 a and 24 b of actuation surface 24and are opened or occluded by respective valves 34 a and 34 b. AY-connection or branch line 124 c, a second dialysis fluid containerline 124 d, a third dialysis fluid container line 124 e and a patientline 124 f extend and connect to their respective ports 114 c to 114 f,which communicate fluidly with lower chamber 110 b. Y-connection orbranch line 124 c, second dialysis fluid container line 124 d, thirddialysis fluid container line 124 e and patient line 124 f are routedrespectively in grooves 24 c to 24 f of actuation surface 24 and areopened or occluded by respective valves 34 c to 34 f.

Peristaltic pumping tube 124 gh or line extends between and connects torespective ports 114 g and 114 h of the upper chamber 110 a and lowerchamber 110 b. In an embodiment, peristaltic pump actuator 30 located atthe actuation surface of APD cycler 20 rotates in a first direction(clockwise in FIGS. 1 and 3 ) to pump fresh, heated dialysis fluid fromupper chamber 110 a, through the peristaltic pumping tube 124 gh, tolower chamber 110 b, and to the patient. Peristaltic pump actuator 30rotates in the opposite direction (counterclockwise in FIGS. 1 and 3 )to pump used dialysis fluid from lower chamber 110 b, through theperistaltic pumping tube 124 gh, to upper chamber 10 a, and to drain(used dialysis fluid or effluent) or to a heater for heating (freshdialysis fluid).

FIG. 3 also illustrates that manifold assembly 100 includes draincontainer 126 a located at the distal end of drain tube or line 124 a.Drain line 124 a extends alternatively to a house drain, such as thepatient's toilet, bathtub or sink. Fresh dialysis fluid containers 126b, 126 d and 126 e are located respectively at the distal ends of first,second and third dialysis fluid container lines 124 b, 124 d and 124 e.Fresh dialysis fluid containers or bags 126 b, 126 d and 126 e may holddifferent types and quantities of fresh dialysis fluid, such asdifferent dextrose or glucose levels or formulations, e.g., container126 e may contain icodextrin, which is used for the patient's last fill.Containers 126 b or 126 d may for example hold multiple fill volume'sworth of fresh dialysis fluid.

Patient line or tube 124 f extends to a patient line connector 126 f,which may for example connect to a patient's transfer set leading to anindwelling catheter that extends to the patient's peritoneal cavity.FIG. 3 also illustrates that in addition to air sensor 36, patient lineor tube 124 f may also operate with a pressure sensor 38, which may beprovided alternatively or in addition to membranes covering holes 118 aand 118 b and operating with pressure transducers located at actuationsurface 24 for controlling patient pumping pressure as has beendiscussed herein. A second air sensor 36 may also operate with dialysisfluid container/heater line 124 b to look for air that comes out ofsolution due to the heating of the fresh dialysis fluid. First andsecond air sensors 36 may be provided alternatively to or in addition tothe air detection via capacitance sensing discussed herein.

FIG. 3 schematically illustrates fresh dialysis fluid container or bag126 b operating with a dialysis fluid heater 40. FIG. 1 illustrates thatheater 40 is located on top of housing 22 of cycler 20 in oneembodiment. In an alternative embodiment, heater 40 may be locatedseparate from housing 22, e.g., as a warming blanket or pouch. In eithercase, heater 40 is in one embodiment a resistive plate heater, which isconfigured to heat a fill volume's quantity of fresh dialysis fluid(e.g., one to two liters) from ambient temperature to body temperature(e.g., 37° C.), for example, during a current patient dwell phase sothat heated dialysis fluid is ready as soon as the patient is drainedafter the current dwell phase. One or more temperature sensor 42operates with heater 40 to provide feedback for controlling the heater,e.g., using a proportional, integral, derivative control algorithm.

In FIG. 3 , peristaltic pump actuator 30 rotates in the counterclockwisedirection to pump fresh dialysis fluid from either of the second orthird dialysis fluid containers 126 d or 126 e into lower chamber 110 b,through peristaltic pumping tube 124 gh, to upper chamber 110 a, and tothe previously emptied first dialysis fluid container 126 d, which isplaced in operable communication with dialysis fluid heater 40. Byallowing the fresh dialysis fluid from each of the dialysis fluidcontainers 126 b, 126 d and 126 e to be heated in first dialysis fluidcontainer or bag 126 b, the disposable dialysis fluid set of manifoldassembly 100 only has to be loaded once for operation. Additionally, aseparate dialysis fluid heating container or bag is not needed.

In one embodiment, first dialysis fluid container or bag 126 b is loadedonto dialysis fluid heater 40 for an initial patient fill. After firstdialysis fluid container 126 b is emptied, peristaltic pump actuator 30reverses and pulls fresh dialysis fluid from second dialysis fluidcontainer 126 d and pushes same into first dialysis fluid container 126b for heating. The same procedure is performed for third dialysis fluidsupply container 126 e when second dialysis fluid supply container 126 dis emptied. If the dialysis fluid from the second 126 d (or third 126 e)container is different than that of first container 126 b, Y-connectionor branch line 124 c is used to enable the remaining fluid from firstdialysis fluid container 126 b to be pulled by the peristaltic pumpactuator 30 into lower chamber 110 b and then pushed into upper chamber110 a and out to drain 126 a before the differently formulated fluid ofthe second 126 d (or third 126 e) dialysis fluid container is deliveredto first dialysis fluid container 126 b for heating. In the illustratedembodiment of FIG. 3 , Y-connection or branch line 124 c branches offdialysis fluid container/heater line 124 b, e.g., via a Y-connector, andextends to bypass or branch line port 114 c communicating with lowerchamber 110 b.

FIG. 2A illustrates that sensor portions 116 s of the rigid plastic wall116 for each of upper chamber 110 a and lower chamber 110 b are notprovided with pegs 122 and serve as a capacitive sensing areas for therespective upper chamber 110 a and lower chamber 110 b. Each of thecapacitive sensing portions 116 s of the rigid plastic wall 116 duringoperation presses up against a capacitive sensing plate or electrodelocated along actuation 24 surface of APD cycler 20. Door 26 of APDcycler 20 is provided with a matching capacitive sensing plate orelectrode for each chamber 110 a and 110 b, which each directly opposethe capacitive sensing plates located along actuation surface 24. Thematching upper and lower sets or pairs of capacitive sensing plates orelectrodes form upper and lower capacitive sensors. The capacitivesensors, one for each chamber 110 a and 110 b, detect an amount of airin the respective chamber. If too much air accumulates in chamber 110 a,APD cycler 20 stops its current routine and causes peristaltic pumpactuator 30 with drain line valve 34 a open to rotate in acounterclockwise direction in FIG. 3 to push the air to drain 126 a viadrain line or tube 124 a.

FIG. 4 illustrates rigid plastic manifold 110 from the side showing itsoperation with a first pair of capacitive sensing plates or electrodes44 a and 44 b for first or upper chamber 110 a and a second or lowerpair of capacitive sensing plates or electrodes 46 a and 46 b for secondor lower chamber 110 b. In the illustrated embodiment, sensing plates orelectrodes 44 a and 46 a of each sensor pair located along actuationsurface 24 are active capacitor plates or electrodes and connectelectrically to a signal line 48 a leading to a capacitance sensingcircuit 60 of a control unit 50. Sensing plates or electrodes 44 b and46 b of each sensor pair located along door 26 are ground capacitorplates or electrodes and connect electrically to a ground line 48 bleading to a ground within door 26, which communicates electrically withthe ground of housing 22. Active plates or electrodes 44 a and 46 a ofeach sensor pair abut against capacitive sensing portions 116 s of therigid plastic wall 116 of upper and lower chambers 110 a and 110 brespectively. Ground plates or electrodes 44 a and 46 a of each sensorpair are parallel to and directly oppose active plates or electrodes 44a and 46 a. Ground plates or electrodes 44 a and 46 a abut againstflexible (or rigid) plastic sheet 112 that extends along respectiveupper and lower chambers 110 a and 110 b. In an alternative embodiment,ground plates or electrodes 44 a and 46 a are merged into a singleground plate or electrode.

In general, the capacitance between (i) plates or electrodes 44 a and 44b and (ii) plates or electrodes 46 a and 46 b is calculated using theequation:

C=(ε_(r)×ε₀ ×A)/d, wherein

ε_(r) is the dielectric constant of the material between the plates orelectrodes, ε₀ is the permittivity of free space (8.85×10⁻¹² F/m), A isthe area of the plates or electrodes, and d (shown in FIG. 4 ) is theseparation between the plates or electrodes (in meters). As illustratedby Table 1, air and water/dialysis fluid have very different dielectricconstants.

TABLE 1 dielectric constants: water 80 air 1 metal infinite paper 3.7acrylic 2 to 5As the liquid level rises or falls between (i) plates or electrodes 44 aand 44 b and (ii) plates or electrodes 46 a and 46 b, the capacitancebetween the plates changes.

FIG. 4 illustrates (i) plates or electrodes 44 a and 44 b abuttingdirectly against capacitive sensing portions 116 s of rigid plastic wall116 and plastic sheet 112, respectively, and (ii) plates or electrodes46 a and 46 b abutting directly against capacitive sensing portions 116s of rigid plastic wall 116 and plastic sheet 112, respectively. It isexpressly contemplated to provide the direct abutting illustrated inFIG. 4 . Table 1 shows however that plastic, such as acrylic, has a verylow dielectric compared to that of water or dialysis fluid. The plasticwalls of rigid plastic manifold 110 therefore do not adversely affectthe performance of the capacitive sensors. Likewise, performance is notadversely effected if plates or electrodes 44 a and 44 b and plates orelectrodes 46 a and 46 b are abutted instead inside thin plastic wallsprovided by actuation surface 24 and door 26, wherein the thin plasticwalls instead abut rigid plastic manifold 110. This latter configurationmay be desired to protect the metal plates or electrodes 44 a, 44 b, 46a and 46 b.

Signal lines 48 a in FIG. 4 extend to capacitance sensing circuit 60 ofa control unit 50. Control unit 50 (also illustrated in FIG. 1 )includes one or more processor 52, one or more memory 54 and a videocontroller 56 that controls a user interface 58, such as a touch screenuser interface. User interface 58 may alternatively or additionally be aremote user interface, e.g., via a tablet or smartphone. Control unit 50also includes capacitance sensing circuits 60 that each receives signalsalong a signal line 48 from one of the capacitive plate pairs. Controlunit 50 is programmed to use the signals to look for air duringtreatment and to run any one or more of the calibration proceduresdiscussed here. Control unit 50 receives signals from other sensors,such as (i) pressure sensors via holes and pressure transmissionmembranes 118 a and 118 b and/or pressure sensor 38 to control patientpumping pressure and other pumping pressures discussed above via thecontrol of current to peristaltic pump motor 32, (ii) one or moretemperature sensor 42 to control dialysis fluid heater 40 to heat freshdialysis fluid to body temperature, e.g., 37° C., and (iii) possiblyadditional air sensors 36.

Control unit 50 may also include a transceiver and a wired or wirelessconnection to a network (not illustrated), e.g., the internet, forsending treatment data to and receiving prescriptioninstructions/changes from a doctor's or clinician's server interfacingwith a doctor's or clinician's computer. The data sent to the doctor'sor clinician's computer may be analyzed and/or converted to, or used toform, other data useful for analysis. Such data conversion is performedalternatively at control unit 50.

FIG. 5 illustrates one embodiment of capacitance sensor circuit 60,which in the illustrated encompasses the capacitive sensors of bothupper chamber 110 a and lower chamber 110 b. Capacitance sensor circuit60 includes signal line 48 a leading from active capacitor electrode orplate 44 a, signal line 48 a leading from active capacitor electrode orplate 46 a, ground line 48 b leading from ground electrode or plate 44b, and ground line 48 b leading from ground electrode or plate 46 b, asdescribed above in connection with FIG. 4 . Signal lines 48 a leadingfrom the active capacitor electrode or plate each lead to an L-Csubcircuit 70.

The L-C subcircuits 70 are used by an FDC2214 integrated circuit 80,forming capacitance sensor circuit 60. L-C subcircuits 70 each includean inductor 72 (“L”) and a capacitor 74 (“C”). A corresponding L-Coscillation frequency f₀ depends on total inductance L and totalcapacitance C according to the following equation:

$f_{0} = \frac{1}{2\pi\sqrt{LC}}$

The values of L and C are chosen to provide a desirable range ofoscillation frequencies. As the liquid level changes between activeplates 44 a, 46 a and ground plates 44 b, 46 b, the capacitance betweenthe plates will change. The change in capacitance results in differentresonant frequencies f₀, which are measured by FDC2214 integratedcircuit 80. L-C subcircuits 70 set the range of resonant frequencies f₀measured. From the frequencies f₀ measured by FDC2214 integrated circuit80, one or more processor 52 and one or more memory 54 of control unit50 calculate the capacitance and the corresponding liquid level withinupper chamber 110 a and lower chamber 110 b.

L-C subcircuits 70 provide a number of advantages. L-C subcircuits 70provide excellent immunity to electromagnetic interference (“EMI”). L-Csubcircuits 70 also allow the operating frequency f₀ to be shifted ifneeded to avoid noise source interference.

In addition to the detection of air, the APD system 10 of the presentdisclosure uses capacitive sensing, including capacitance sensor circuit60 and control unit 50, to calibrate peristaltic pump actuator 30, whichis performed in one embodiment when enough air builds in the upperchamber 110 a that an air purge to drain needs to be performed. Here,control unit 50 causes peristaltic pump actuator 30 as viewed in FIGS. 1and 3 to rotate in a counterclockwise direction to pull fresh or useddialysis fluid from lower chamber 110 b into upper chamber 110 a ofrigid plastic manifold 110, to purge air to drain 126 a. Control unit 50uses a capacitance sensor circuit 60 with upper capacitive sensingplates or electrodes 44 a and 44 b to determine a volume of fresh orused dialysis fluid delivered to upper chamber 110 a and counts thenumber of pump strokes, including any partial pump stroke. Regardingpartial pump strokes, it is contemplated to provide an encoder for usewith peristaltic pump motor 32, wherein the encoder allows a fullrevolution of 360° to be divided into many fractions of a rotation,e.g., into 5919 fractions. Control unit 50 then divides the volumedetermined via capacitance sensor circuit 60 by the number of pumpstrokes to determine the volume per revolution in the counterclockwisedirection. Control unit 50 uses that volume per revolution going forward(multiplying by counted revolutions including partial revolutions) whenrotating the peristaltic pump actuator in the counterclockwisedirection, e.g., for patient draining volume and flowrate determination.Lower capacitive sensor plates 46 a and 46 b may be used additionally(for confirmation) or alternatively to detect how much fluid leaveslower chamber 110 b over the known amount of peristatic pump strokes orrevolutions, so that the volume per revolution of the peristaltic pumpin the same counterclockwise direction may be calculated and used. Lowercapacitive sensor plates 46 a and 46 b and associated circuitry alsoform the primary sensing structure for air detection and mitigationduring treatment.

Control unit 50 then causes peristaltic pump actuator 30 to rotate inthe opposite, clockwise direction as viewed in FIGS. 1 to 3 to pushfluid from upper chamber 110 a into lower chamber 110 b of rigid plasticmanifold 110. Control unit 50 uses a capacitance sensor circuit 60 withupper capacitive sensor plates 44 a and 44 b to detect how much fluidleaves upper chamber 110 a over a known amount of peristatic pumpstrokes or revolutions, including partial revolutions, so that thecurrent volume/stroke of the peristaltic pump in the opposite, clockwisedirection can be calculated and used going forward (multiplying bycounted revolutions including partial revolutions) when rotating theperistaltic pump actuator in the clockwise direction, e.g., for patientfilling. Lower capacitive sensing plates or electrodes 46 a and 46 b maybe used additionally (for confirmation) or alternatively to detect howmuch fluid enters lower chamber 110 b over the known amount ofperistatic pump strokes or revolutions, so that the volume perrevolution of the peristaltic pump in the same clockwise direction maybe calculated or confirmed. Again, Lower capacitive sensing plates orelectrodes 46 a and 46 b may be used primarily for air detection andmitigation during treatment.

In an alternative embodiment, control unit 50 runs a calibrationsequence 150 according to FIG. 6 to calibrate peristaltic pump actuator30. Calibration sequence 150 may be performed at any time when at leastupper chamber 110 a is empty. The volume of upper chamber 110 a isknown. At oval 152, calibration sequence 150 begins. At block 154,control unit 50 causes drain valve drain line valve 34 a and branch linevalve 34 c to open, while all other valves remain closed.

At block 156, control unit 50 causes peristaltic pump actuator 30 asviewed in FIGS. 1 and 3 to run in a counterclockwise direction to pumpfresh dialysis fluid at a known revolutions per minute (“rpm”) for motor32 (e.g., to attempt to pump at 20 ml/min). At block 158, thecounterclockwise movement of pump actuator 30 pulls fresh dialysis fluidfrom dialysis fluid container 126 b into lower chamber 110 b via branchline 124 c.

At block 160, control unit 50 monitors upper capacitive sensing platesor electrodes 46 a and 46 b and their capacitance sensor circuit 60 oncedialysis fluid enters upper chamber 110 a. At block 162, control unit 50while monitoring the upper capacitance sensor also records the timeduration needed to fill upper chamber 110 a. At block 164, control unit50 calculates the flowrate by dividing the known volume of upper chamber110 a by the time duration just recorded. At block 166, control unit 50calculates the volume per revolution in the counterclockwise directionby dividing the just calculated flowrate by the known rpm. At block 168,control unit 50 is programmed to use the just calculated volume perrevolution (multiplying by counted revolutions including partialrevolutions) going forward when pumping in the counterclockwisedirection, e.g., for a patient drain.

At block 170, the above steps of calibration sequence 150 are then berepeated in the opposite, clockwise direction by draining upper chamber110 a and measuring the time duration needed to do so. The rpm or motor32 and the volume of chamber 110 a are again known, so that control unit50 may calculate the volume per revolution in the clockwise direction bydividing the volume of chamber 110 a by the measured time duration fordraining and then dividing the resulting flowrate by the known rpm.Control unit 50 then uses the just calculated volume per revolution(multiplying by counted revolutions including partial revolutions) goingforward when pumping in the clockwise direction, e.g., for a patientfill. At oval 172, method 150 ends.

Referring now to FIG. 7 , a plot showing capacitance sensor output overtime is illustrated, wherein the illustrated duration of time Δt is usedin the calibration procedure of FIG. 6 and sequence 150. Time t₁corresponds to block 160, wherein upper capacitive sensing plates orelectrodes 46 a and 46 b and their capacitance sensor circuit 60 aremonitored once dialysis fluid enters upper chamber 110 a. Time t₂corresponds to the end of the capacitance measuring at block 162,wherein upper chamber 110 a becomes full and the capacitance no longerincreases. The difference between t₂ and t₁ is Δt, which is used inblock 164 to calculate the average flowrate while filling first or upperchamber 110 a.

Referring now to FIG. 8 , a plot comparing capacitance sensor outputagainst a weight scale output for a same fluid fill is illustrated. InFIG. 8 , the output of upper capacitive sensing plates or electrodes 44a and 44 b or lower capacitive sensing plates or electrodes 46 a and 46b operating with their corresponding capacitance sensor circuit 60,while their respective chamber 110 a or 110 b is filled is plottedagainst the output of a weight scale weighing the same filling of thesame chamber. Both the capacitance sensor output and the weight scaleoutput are normalized to [0-1]. FIG. 8 demonstrates a clear matchbetween the two outputs, showing that the capacitance sensors of system10 of the present disclosure are accurate.

Referring now to FIG. 9 , a plot showing an equation stored in softwareat one or more memory 54 for converting an output of a capacitancesensor of the present disclosure to a weight of fluid is illustrated.Here, the weight of the dialysis fluid (y) inside of one of chambers 110a or 110 b is determined from a measured signal value (x) from uppercapacitive sensing plates or electrodes 44 a and 44 b or lowercapacitive sensing plates or electrodes 46 a and 46 b operating withtheir respective capacitance sensor circuit 60 according to thefollowing equation stored in software: y=0.0501x+55.2797.

It should be appreciated that for any calibration embodiment describedherein, the calibration procedure may be run at a flowrate that is lowerthan the flowrates used typically during treatment. For example, thecalibration procedures may be run at 20 ml/min or other lower flowrateknown to produce accurate capacitance readings. Filling and drainingflowrates are typically in the range of 200 ml/min to 250 ml/min. It isalso contemplated for control unit 50 of system 10 to run pressure orflow profiles for at least one of a patient fill and patient drain,which may begin at lower pressures and flowrates, ramp up to higherpressures and flowrates during the middle of the fill or drain, and rampdown to lower pressures and flowrates at the end of the fill or drain.The beginning and end of the patient fills and drains are when thepatient is most sensitive. Patient fill pressures may for example becontrolled to be less than 1.5 psig at the beginning and/or end, e.g.,for at least one of first and last 10%, of the patient fill, and thenramp up to as high as 9.5 psig during the middle 80% to 90% of the fill.Flowrates may correspondingly start and/or end at around 60 ml/min andthen ramp up to around 200 ml/min to 250 ml/min. Patient drain pressuresmay for example be controlled to be less than −1.5 psig at the beginningand/or end, e.g., for at least one of first and last 10%, of the patientdrain, and then ramp up to as high as −3.0 psig during the middle 80% to90% of the drain.

In one embodiment, control unit 50 of system 10 performs an initialcalibration of peristaltic pump actuator 30 and peristaltic pumping tube124 gh in both counterclockwise and clockwise directions according toany of the embodiments described herein. Next, without knowing if thepatient is full of effluent from a prior treatment or not, control unit50 of system 10 assumes that the patient is full of effluent andautomatically attempts an initial drain, e.g., at a low pressure andflowrate. If the patient is not full of effluent, control unit 50 ofsystem 10 detects same immediately either by sensing a high resistancepressure caused by the empty patient catheter or by detecting air inlower chamber 110 b via the capacitive sensing. Control unit 50 thenproceeds to a patient fill. It is contemplated to recalibrateperistaltic pump actuator 30 and peristaltic pumping tube 124 gh in bothcounterclockwise and clockwise directions during each patient dwell of atreatment.

Referring now to FIG. 10 , an alternative rigid plastic manifold 210 foruse with system 10 is illustrated. Rigid plastic manifold 210 may bemade of any of the materials and processes described herein and includesmany of the same structure, functionality and alternatives discussedabove for rigid plastic manifold 110, wherein those structures arenumbered the same and not repeated here. For example, rigid plasticmanifold 210 includes first chamber 110 a and second chamber 110 b.Additionally, manifold 210 includes a third chamber 110 c that islocated, e.g., molded, on top of the former upper chamber 110 a, makingit now the middle chamber of third chamber manifold 210. One or moreaperture 212 is formed between first or middle chamber 110 a and thirdor upper chamber 110 c, however, it is contemplated that fluid does notflow from middle chamber 110 a to the upper, third chamber 110 c.Instead, upper chamber 110 c is provided to supply air to middle chamber110 a during a calibration sequence discussed below.

FIG. 10 illustrates that it is contemplated to move pressure sensinghole and accompanying pressure sensing membrane 118 a from upper chamber110 a of two chamber manifold 110 to upper chamber 110 c of threechamber manifold 210. In an alternative embodiment, pressure sensinghole and accompanying pressure sensing membrane 118 a remains in firstchamber 110 a and a third pressure sensing hole and accompanyingpressure sensing membrane is added to upper chamber 110 c of the threechamber manifold 210.

In an embodiment, rigid manifold 210 provides capacitive sensingportions 116 s along rigid plastic wall 116, which operate with uppercapacitive sensing plates or electrodes 44 a and 44 b and lowercapacitive sensing plates or electrodes 46 a and 46 b and theircapacitance sensor circuit 60. Lower capacitive sensing plates orelectrodes 46 a and 46 b my again be provided mainly for air detectionand mitigation during treatment. In an alternative embodiment for bothrigid manifolds 110 and 210 of system 10, only upper capacitive sensingplates or electrodes 44 a and 44 b for first chamber 110 a are provided.Here, the lower capacitive sensor for chamber 110 b is not provided. Ineither case for manifold 210, added upper chamber 110 c is not intendedto hold fluid and does not operate with capacitive sensing plates orelectrodes accordingly in one embodiment.

FIG. 11 illustrates alternative manifold assembly 200 of system 10 usingalternative rigid manifold 210. Here again, the tubing and containers ofmanifold assembly 200 may be made of any of the materials and processesdescribed herein and includes many of the same structure, functionalityand alternatives discussed above for manifold assembly 100, whereinthose structures are numbered the same and not repeated here. Theoperation and control of valves 34 a to 34 f, peristaltic pump actuator30 and heater 40 for (i) pumping fresh dialysis fluid to heater 40 forheating, (ii) pumping heated, fresh dialysis fluid to the patient, (iii)pumping used dialysis fluid to drain, (iv) removing leftover freshdialysis fluid from dialysis fluid container 126 b to drain, and (v)removing air to drain is performed for system 10 using alternativemanifold assembly 200 in the same manner as described above for system10 using manifold assembly 100.

FIGS. 12A to 12C illustrate one possible peristaltic pump calibrationprocedure performed under control of control unit 50 using alternativerigid manifold 210 and manifold assembly 200. Third, upper chamber 110 cis added to help perform the calibration procedure. In a first step ofthe calibration procedure as illustrated in FIG. 12A, fresh dialysisfluid is pulled from one of the dialysis fluid containers 126 b, 126 dor 126 e to prime middle chamber 110 a and lower chambers 110 bcompletely, as determined using the upper capacitance sensor alone or incombination with the lower capacitance sensor, so that all air is pushedto drain.

In a next step illustrated in FIG. 12B, pinch valve 34 c for branch line124 c leading from first dialysis fluid container 126 b to lower chamber110 b is opened, and peristaltic pump actuator 30 is actuated at a knownrevolutions per minute (“rpm”) in a first direction (clockwise in FIG.11 ) so as to move dialysis fluid from middle chamber 110 a to lowerchamber 110 b until the middle chamber is completely empty as measuredby capacitive sensing plates or electrodes 44 a and 44 b and capacitancesensor circuit 60, wherein (i) dialysis fluid in lower chamber 110 bmigrates through open branch line 124 c into first dialysis fluidcontainer 126 b, (ii) air from the third, upper chamber 110 c is pulledinto middle chamber 110 a, and (iii) flexible (or rigid) sheet 112extended to cover third chamber 110 c bows inward into the upper chamberto compensate for the air that moves from upper chamber 110 c intomiddle chamber 110 b. The volume of the middle chamber (V_(m)) is knownand the time duration (Δt) needed to fully drain middle chamber 110 a ismeasured at control unit 50. Knowing those two parameters and the rpm ofperistaltic pump actuator 30 actuated in the chamber draining direction(clockwise) allows the stroke volume per revolution in the chamberdraining direction to be calculated, namely, to be equal toV_(m)/Δt/rpm, e.g., in milliliters (“ml”)/rpm.

In a next step illustrated in FIG. 12C, wherein pinch valve 34 c forbranch line 124 c leading from first dialysis fluid container 126 b tolower chamber 110 b remains open, peristaltic pump actuator 30 isactuated at a known revolutions per minute (“rpm”) in a second direction(counterclockwise in FIG. 11 ) so as to move dialysis fluid from lowerchamber 110 b to middle chamber 110 a until the middle chamber iscompletely full as measured by capacitive sensing plates or electrodes44 a and 44 b and capacitance sensor circuit 60, wherein (i) dialysisfluid from first dialysis fluid container 126 b flows through openbranch line 124 c into the lower chamber 110 b and from the lowerchamber into middle chamber 110 a, (ii) air is pushed from middlechamber 110 a into upper chamber 110 c, and (iii) flexible (or rigid)sheet 112 straightens within upper chamber 110 c due to the air beingpushed into the upper chamber by the dialysis fluid entering middlechamber 110 a. The volume of middle chamber 110 a (V_(m)) is known andthe time (Δt) needed to fully fill the middle chamber is measured atcontrol unit 50. Knowing those two parameters and the rpm of peristalticpump actuator 30 actuated in the chamber filling direction(counterclockwise) allows the stroke volume per revolution in thechamber filling direction to be calculated, namely, to be equal toV_(m)/Δt/rpm, e.g., in ml/rev.

Control unit 50 is configured to use the results of the peristaltic pumpcalibration procedures discussed in connection with FIGS. 12A to 12C andin the other embodiments going forward to determine how much fresh PDfluid is delivered to the patient and how much used PD fluid is removedfrom the patient. That is, knowing the latest volume per revolution,control unit 50 thereafter counts the number of revolutions (includingpartial revolutions) over a patient fill or patient drain and multiplesthat number times the latest volume per revolution to determine thevolume of fluid filled to or drained from the patient. It should beappreciated that volume per revolution could instead be weight perrevolution (grams/rev), wherein the weight of fresh or used dialysisfluid within a particular chamber of the manifold is known.

Manifold assembly 100 and alternative manifold assembly 200 in theillustrated embodiments are closed with respect to outside ambient airand rely on air generated or existing within rigid plastic manifolds 110and 210 to perform the peristaltic pump accuracy calibration sequencesdiscussed herein. Referring now to FIGS. 13A to 13C, a first unlimitedair manifold 310 for use with alternative manifold assembly 300 ofalternative system 10 is illustrated. Rigid plastic manifold 310 may bemade of any of the materials and processes described herein and includesmany of the same structures, functionality and alternatives discussedabove for rigid plastic manifold 110, wherein those structures arenumbered the same and may not be repeated here. For example, rigidplastic manifold 310 includes first chamber 110 a and second chamber 110b, each covered via a flexible (or rigid) plastic sheet 112. Rigidplastic manifold 310 also includes drain port 114 a, first heaterline/first dialysis fluid container port 114 b, bypass or branch lineport 114 c, second dialysis fluid container port 114 d, third dialysisfluid container port 114 e, patient line port 114 f and peristaltic pumpports 114 g and 114 h. Rigid plastic manifold 310 further includes rigidplastic wall 116 having sensing portions 116 s, and walls 120 a and 120b provided to help guide dialysis fluid and air flow. Rigid plasticmanifold 310 also includes pegs 122 extending inwardly from the rigidplastic wall 116, which prevent flexible plastic sheet 112 fromcollapsing under negative pressure. In the instance in which plasticsheet 112 is instead a rigid plastic lid, pegs 122 are not needed orprovided.

In the illustrated embodiment, rigid plastic manifold 310 of alternativemanifold assembly 300 additionally includes an air port 114 appositioned and arranged to allow filtered, ambient air to be pulled intoupper chamber 110 a. An air port line or tube 124 p is made of any ofthe materials discussed herein and is sealed to air port 114 ap via anytechnique described herein, e.g., ultrasonically, via heat seal oradhesively. Air port line or tube 124 ap may be short, e.g., long enoughto interact with a pinch valve. A filter connector 130 is likewise ismade of any of the materials discussed herein and is sealed to the endof air port line or tube 124 ap via any technique described herein.Filter connector 130 in the illustrated embodiment includes a filterhousing 132, which houses a hydrophobic filter 134. Hydrophobic filter134 is configured to allow air but not liquid, e.g., dialysis fluid, topass through housing 132. Hydrophobic filter 134 also filters andpurifies ambient air entering rigid plastic manifold 310 via air portline or tube 124 ap, so that the air may interface with sterilizeddialysis fluid.

Any of the manifolds 110, 210, 310, 410 and 510 discussed herein mayinclude material removal openings 128 to reduce disposable cost.

FIGS. 13A and 13B illustrate that APD cycler 20 provides an air portvalve 34 ap that operates with air port line or tube 124 ap. Air portvalve 34 ap, like the other valves, is under control of control unit 50and may be an electrically actuated solenoid pinch valve, which opens ina fail safe manner upon being energized. Pinch valve 34 ap is typicallyclosed during treatment to prevent air from entering manifold assembly300 and fresh or used dialysis fluid from reaching filter connector 130and hydrophobic filter 134. Control unit 50 opens pinch valve 34 ap andruns peristaltic pump head or actuator 30 in a clockwise direction topull air into upper chamber 110 a at any time it is desired to calibratethe peristaltic pump actuator. In an embodiment, control unit 50 closesall other pinch valves 34 a to 34 f when pulling air into manifoldassembly 300.

The above structure allows for an unlimited supply of air to be providedat any desired time. Volumetric calibration may therefore be performedat any time prior to the start of therapy and, for example, duringperitoneal dialysis treatment dwells. Manifold assembly 300 allows formultiple calibration attempts (e.g., for averaging), at multiple pumpactuator speeds, and in both pump directions. If an initial calibrationsequence fails, for example, manifold assembly 300 allows for animmediate subsequent calibration sequence with the same disposable,which reduces treatment delays and disposable scrap.

Referring now to FIGS. 14A and 14B, a second unlimited air manifold 410for use with an alternative manifold assembly 400 of alternative system10 is illustrated. Rigid plastic manifold 410 may be made of any of thematerials and processes described herein and includes many of the samestructures, functionality and alternatives discussed above for rigidplastic manifold 110, wherein those structures are numbered the same andmay not be repeated here. For example, rigid plastic manifold 410includes first chamber 110 a and second chamber 110 b, each covered viaflexible (or rigid) plastic sheet 112. Rigid plastic manifold 410 alsoincludes drain port 114 a, first heater line/first dialysis fluidcontainer port 114 b, bypass or branch line port 114 c, second dialysisfluid container port 114 d, third dialysis fluid container port 114 e,patient line port 114 f and peristaltic pump ports 114 g and 114 h.Rigid plastic manifold 410 further includes rigid plastic wall 116having sensing portions 116 s, and walls 120 a and 120 b provided tohelp guide fluid and air flow. Rigid plastic manifold 410 also includespegs 122 extending inwardly from rigid plastic wall 116, which preventflexible plastic sheet 112 from collapsing under negative pressure. Inthe instance in which plastic sheet 112 is instead a rigid plastic lid,pegs 122 are not needed or provided.

In the illustrated embodiment, second unlimited air manifold 410 ofalternative manifold assembly 400 of system 10 additionally includes adedicated air port 114 ap located on back wall 116 of the manifold.Dedicated air port 114 ap is routed to upper chamber 110 a of manifold410 via a molded air pathway 412. A hydrophobic air filter 414 isattached to the back of air port 114 ap. Hydrophobic filter 414 isconfigured to allow air to be pulled into upper chamber 110 a and toprevent fresh or used dialysis fluid from escaping manifold 410 intocycler 20. Hydrophobic filter 414 also filters and purifies ambient airentering rigid plastic manifold 410, so that the air may interface withsterilized dialysis fluid.

Cycler 20 operating with manifold assembly 400 provides a seal (notillustrated), e.g., a spring closed and pneumatically opened seal, tonormally seal the hydrophobic filter 414 closed. Cycler 20 provides apneumatic pump and possibly a pneumatic supply tank to supply, e.g.,negative pressure to overcome the spring force and pull the seal fromhydrophobic filter 414 to expose the filter to ambient air. Cycler 20accordingly includes at least one pneumatic valve under control ofcontrol unit 50 to open and close a pneumatic line leading to the seal.The pneumatic valve is normally closed until air is needed in rigidplastic manifold 410 for a volumetric calibration. Peristaltic pumpactuator 30 is operated again in a clockwise direction to draw in airinto top chamber 110 a at any time and for any amount of air needed forthe volumetric calibration.

Referring now to FIG. 15 , a further alternative rigid manifold 510 foruse with an alternative manifold assembly 500 of alternative system 10is illustrated. Rigid plastic manifold 510 may be made of any of thematerials and processes described herein and includes many of the samestructures, functionality and alternatives discussed above for rigidplastic manifold 110, wherein those structures are numbered the same andmay not be repeated here. For example, rigid plastic manifold 510includes first chamber 110 a and second chamber 110 b, which in theillustrated embodiment are each covered via a rigid plastic sheet 112(could alternatively be flexible). Rigid plastic manifold 510 alsoincludes drain port 114 a, first heater line/first dialysis fluidcontainer port 114 b, bypass or branch line port 114 c, second dialysisfluid container port 114 d, third dialysis fluid container port 114 e,patient line port 114 f and peristaltic pump ports 114 g and 114 h.Rigid plastic manifold 510 further includes rigid plastic wall 116having sensing portions 116 s, and walls 120 a and 120 b provided tohelp guide fluid and air flow. Rigid plastic manifold 510 does notrequire pegs 122 if employing a rigid front wall 112. Pegs 122 areprovided if plastic wall 112 is flexible.

Rigid plastic manifold 510 also includes pressure sensing aperture 118a, such as a circular hole, formed or provided in rigid plastic wall 116of upper chamber 110 a, which is covered with a pressure sensingmembrane. When manifold 510 is mounted to APD cycler 20 for operation,the pressure sensing membrane covering hole 118 a abuts against apressure transducer provided by the cycler at actuation surface 24.Rigid plastic manifold 510 further includes dedicated air port 114 aplocated on back wall 116 of the manifold. Dedicated air port 114 ap isrouted to upper chamber 110 a of manifold 410 via a molded air pathway412. Hydrophobic air filter 414 is attached to the back of air port 114ap to allow air to be pulled into upper chamber 110 a and to preventfresh or used dialysis fluid from escaping manifold 410 into cycler 20.

In the illustrated embodiment, pressure sensing aperture 118 b is notprovided in lower chamber 110 b. Pressure sensing aperture 118 b isprovided instead in back wall 116 adjacent to air port 114 ap. Pressuresensing aperture 118 b with manifold 510 is covered by a hydrophobicfilter instead of an air impermeable pressure sensing membrane. Whenmanifold 510 is mounted to APD cycler 20 for operation, the hydrophobicfilter covering hole 118 b is placed in registry with a pressuretransducer provided by the cycler at actuation surface 24. Pressuresensing aperture 118 b and its hydrophobic filter covering are in fluidcommunication with lower chamber 110 b via an air channel 512 locatedbetween wall 120 a and an outer wall 120 o of rigid plastic manifold510. Air channel 512 leading upward to pressure sensing aperture 118 band its hydrophobic filter covering aids in the sensing of fresh or useddialysis fluid pressure delivered to or removed from the patient,respectively, by providing a direct communication with the pressuretransducer and the air pressurized via the pressure of fresh or useddialysis fluid in lower chamber 118 b via the hydrophobic filter. Thereis no dependence on the elastic properties of an air impermeable plasticmembrane on the disposable to transduce the pressure signal. Here, thefresh or used dialysis fluid compresses or expands the air withinchannel 512, which has direct communication to the pressure transducerof the cycler via the hydrophobic filter.

As discussed above, control unit 50 in one embodiment includes atransceiver and a wired or wireless connection to a network, e.g., theinternet, for sending treatment data to and receiving prescriptioninstructions from a doctor's or clinician's server interfacing with adoctor's or clinician's computer. In particular for system 10, it iscontemplated for control unit 50 to send data over the network regardingan analysis of the patient's effluent, wherein the data is used todetermine the effectiveness of the patient's APD treatment. The doctoror clinician may review the data to determine if the patient'sprescription should be modified, e.g., dwell times modified and/or achange in dialysis fluid formulation. The data sent from APD cycler 20,though the network to the doctor or clinician may be the same as, orakin to, data obtained from a peritoneal equilibration test (“PET”).

PETs determine the mass transport characteristics associated with thepatient's peritoneum. PETs help doctors and clinicians to decide whethera patient's PD treatment may be improved, e.g., using different dwelltimes and/or different PD fluid formulation. A full PET may take aroundfive hours to complete and may involve a CAPD exchange for example usinga 2.27% glucose solution. Samples of PD fluid and patient blood aretaken at set times. It is known that classical parameters of peritonealtransport such as glucose reabsorption and creatinine transport have adirect correlation with the ionic conductivity of patient effluent.Conductivity has also been used to distinguish patients with and withoutultrafiltration failure.

The capacitive sensing associated with the dual chamber manifold 110 andthree chamber 210 of system 10 provide an opportunity determine theconductivity associated with both the fresh and used dialysis fluid andto use the measured and determined conductivities to develop data andsend the data via a network to locations that have the need and abilityto clinically analyze the data for the reasons discussed above. Inparticular, capacitive sensing plates or electrodes 44 a and 44 b and 46a and 46 b and associated capacitance sensor circuits 60 provide ameasure of a liquid dielectric constant from which a conductivity valuecan be derived.

FIGS. 16 and 17 illustrate how capacitance is dependent on thedielectric properties of dialysis fluid and air in a model thatrepresents chambers 110 a and 110 b. In particular, capacitance C_(meas)is a function of (height of the dialysis fluid h_(W) multiplied by thedielectric of the dialysis fluid ε_(w)) plus (maximum height of thedialysis fluid h_(L) less h_(W)) multiplied by the dielectric of airε_(α).

It is known that there is a relationship between the conductivity andthe dielectric of a fluid. Conductivity is used as a measure todetermine the effectiveness of a peritoneal dialysis treatment. FIGS. 18and 19 are plots of the outputs of the capacitance sensors of thepresent disclosure having capacitive sensing plates or electrodes 44 aand 44 b and 46 a and 46 b and associated capacitance sensor circuits 60versus water (FIG. 18 ) and dialysis fluid (FIG. 19 ) at differentsodium (conductivity) levels. Conductivity clearly has an effect theoutput of the capacitance sensors of the present disclosure.

It is accordingly contemplated to use an empirical model that relates aparticular capacitance reading via 44 a and 44 b and/or 46 a and 46 band associated capacitance sensor circuits 60 to a data point that isused to determine the effectiveness of a peritoneal dialysis treatment.The software employing the model may be installed at control unit ofcycler 50, wherein the converted effectiveness data is sent to thedoctor or clinician, or may be installed at the doctor or cliniciancomputer, wherein the capacitance readings are sent to the doctor orclinician for conversion into effectiveness data.

One possible peritoneal effectiveness test procedure programmed oncontrol unit 50 of system 10 causes first and second chambers 110 a and110 b of manifold 110 or 210 to be filled with fresh dialysis fluid,after which a capacitance measurement (f_(fresh)) is taken usingcapacitive sensing plates or electrodes 44 a and 44 b and/or 46 a and 46b and associated capacitance sensor circuits 60. That fluid is drainedafter which control unit 50 cases both first and second chambers 110 aand 110 b of manifold 110 or 210 to be filled with patient effluent,after which a second capacitance measurement (f_(effluent)) is takenusing capacitive sensing plates or electrodes 44 a and 44 b and/or 46 aand 46 b and associated capacitance sensor circuits 60. Control unit 50then determines a difference between the two readings(Δf=f_(fresh)−f_(effluent)), records same in one or more memory 54 ofAPD cycler 20 and sends same via the network to the doctor's orclinician's computer for clinical analysis. Alternatively, control unit50 converts Δf into effectiveness data using the empirical model andsends the peritoneal dialysis effectiveness data via the network to thedoctor's or clinician's computer for clinical analysis.

The peritoneal effectiveness evaluation is advantageous for at leastthree reasons. First, the evaluation may be performed on a regularbasis, even per treatment or per patient drain if desired, withouthaving to make the patient travel to have a test performed. Second, thetest is easy to perform such that it does not unduly interrupttreatment. Third, the capacitance measurement is non-invasive, that is,it does not require a probe or electrode to contact the fluid beingsensed as is the case with typical conductivity sensors. Sterility andcost issues with such contact are thus avoided.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. It is therefore intended that such changes andmodifications be covered by the appended claims. For example, while theembodiments described herein set forth two capacitance sensors (twopairs of capacitive sensing plates or electrodes), a single capacitancesensor (one pair of capacitive sensing plates or electrodes) may beprovided instead. In another example, while the capacitance sensors havebeen described herein operating with a two or three chamber rigidmanifold, the capacitance sensors may operate alternatively with asingle chamber rigid manifold. In a further example, while the valveshave been described herein as pinch valves, other types of valves may beused alternatively, e.g., volcano valves provided with rigid plasticmanifold 110, 210, 310, 410 and 510. Moreover, while the calibrationsequences or routines discussed herein apply to peristaltic pumpactuation, use of the capacitance sensors of the present disclosure tolook for air to purge may be used with any type of dialysis fluidpumping, e.g., membrane, volumetric, piston, etc.

The invention is claimed as follows:
 1. A peritoneal dialysis (“PD”)system comprising: a cycler including an actuation surface having aperistaltic pump actuator; a manifold assembly including a rigidmanifold having first and second chambers, the rigid manifold configuredand arranged to be abutted against the actuation surface for operation,a peristaltic pump tube extending from the first chamber to the secondchamber of the rigid manifold, a dialysis fluid container line extendingfrom the first chamber, and a branch line extending between the dialysisfluid container line and the second chamber; and a control unitconfigured to cause the peristaltic pump actuator to actuate theperistaltic pump tube to pump dialysis fluid from the branch line intothe second chamber and from the second chamber into the first chamber.2. The PD system of claim 1, wherein when the rigid manifold is abuttedagainst the actuation surface for operation, the first chamber is anupper chamber and the second chamber is a lower chamber.
 3. The PDsystem of claim 1, wherein the rigid manifold includes at least oneflexible sheet surface.
 4. The PD system of claim 3, wherein at leastone of the first and second chambers of the rigid manifold includes atleast one peg extending inwardly to prevent the flexible sheet fromcollapsing under negative pressure.
 5. The PD system of claim 1, whereinat least one of the first or second chambers of the rigid manifoldincludes a pressure sensing hole and a pressure sensing membranecovering the pressure sensing hole, the at least one pressure sensingmembrane placed in registry with a corresponding at least one pressuretransducer when the rigid manifold is abutted against the actuationsurface for operation.
 6. The PD system of claim 1, which includes anair channel extending from one of the first or second chambers to apressure sensing hole and a hydrophobic filter covering the pressuresensing hole, the hydrophobic filter placed in registry with acorresponding pressure transducer when the rigid manifold is abuttedagainst the actuation surface for operation, and wherein the hydrophobicfilter allows for direct pressure communication between the air channeland the pressure transducer.
 7. The PD system of claim 1, which includesa drain line extending from the first chamber of the rigid manifold, andwherein the control unit is configured to cause the peristaltic pumpactuator to actuate the peristaltic pump tube to pump dialysis fluidfrom the branch line into the second chamber, from the second chamberinto the first chamber, and from the first chamber into the drain line.8. The PD system of claim 1, wherein the dialysis fluid container lineis a first dialysis fluid container line, and which includes a seconddialysis fluid container line extending from the second chamber, andwherein the control unit is configured to cause the peristaltic pumpactuator to actuate the peristaltic pump tube to pump dialysis fluidfrom the branch line into the second chamber and from the second chamberinto the first chamber when (i) first dialysis fluid remains in a firstdialysis fluid container in fluid communication with the first dialysisfluid container line after a patient fill and (ii) second dialysis fluidprovided in a second dialysis fluid container in fluid communicationwith the second dialysis fluid container line for a next patient fill isdifferent than the first dialysis fluid.
 9. The PD system of claim 1,wherein the dialysis fluid container line is a first dialysis fluidcontainer line, and which includes a second dialysis fluid containerline extending from the second chamber, and wherein the control unit isfurther configured to cause the peristaltic pump actuator to actuate theperistaltic pump tube to pump dialysis fluid from a second dialysisfluid container in fluid communication with the second dialysis fluidcontainer line into a first dialysis fluid container in fluidcommunication with the first dialysis fluid container line for heatingthe second dialysis fluid.
 10. The PD system of claim 1, wherein thecycler further includes a dialysis fluid heater, the manifold assemblyconfigured such that a dialysis fluid container in fluid communicationwith the dialysis fluid container line is placed on the dialysis fluidheater for treatment.
 11. The PD system of claim 1, which includes apatient line extending from the second chamber of the rigid manifold,and wherein the cycler includes an air sensor positioned and arranged atthe actuation surface to operate with the patient line when the rigidmanifold is abutted against the actuation surface for operation.
 12. ThePD system of claim 1, wherein the cycler includes a dialysis fluidcontainer line valve and a branch line valve positioned and arranged atthe actuation surface to operate with the dialysis fluid container lineand the branch line, respectively, when the rigid manifold is abuttedagainst the actuation surface for operation.
 13. The PD system of claim1, which includes at least one pair of capacitive sensing platesoperable with at least one of the first chamber or the second chamber ofthe rigid manifold when abutted against the actuation surface foroperation, and wherein the control unit is configured to receive asignal from each of the at least one pair of capacitive sensing plates,the at least one signal indicative of an amount of air in at least oneof the first or second chambers.
 14. The PD system of claim 13, whereinthe cycler includes a door that encloses the rigid manifold after therigid manifold is abutted against the actuation surface for operation,the actuation surface containing one of the plates of the at least onepair of capacitive sensing plates, and the door containing the otherplate of the at least one pair of capacitive sensing plates.
 15. The PDsystem of claim 14, wherein the at least one capacitive sensing platecontained by the actuation surface is parallel to and directly opposesthe at least one capacitive sensing plate contained by the door.
 16. ThePD system of claim 1, wherein the rigid manifold includes a thirdchamber, the third chamber configured to at least one of (i) provide airfor backfilling the first chamber when fluid is pumped from the firstchamber to the second chamber during a calibration procedure for theperistaltic pump actuator or (ii) accept air from the first chamber whenfluid is pumped from the second chamber to the first chamber during thecalibration procedure for the peristaltic pump actuator.